The third Monday of the month has been nicknamed Blue Monday as experts reckon it's the gloomiest day of the year.
It's all to do with Christmas being over, the weather being grey and miserable and no-one having much money.
So who or what puts a smile on your face when you're down in the dumps? Is it your friends, family or even your pets?
Maybe there's a sport or activity that always cheers you up or do you know a killer joke that's guaranteed to get us all giggling?
Unfortunately this topic is now closed but there are Comments pages on other subjects on the main Chat index.
"Putting on some loud music and doing crazy dancing makes me happy in the mornings."
Naomi, 13, Kent, England
"My tip is to just ignore the fact it's winter and pretend it's spring or summer and you should feel better."
Thomas, 11, Merseyside, England
"Lately, I've been feeling really depressed. I think it's because I'm back at school again and I've got to catch up. And SATs are getting close which is stressful. So what I do is have a big, long, hot bath with lots of bubbles because I can just relax and forget about all those things!"
Sophie, 11, UK
"You should just live life to the full forget and about all the worries because you only live once. So live life to the full!!!!"
Jess, 14, West Sussex, England
"I'd go out ice skating or to the cinema that will be my idea of happiness."
Melissa, 14, Swansea, Wales
"What I do when I am down in the dumps is I write everything that is annoying me down and then it is is no longer your problem. Just blame it all on the paper!!!"
Amy, 12, Bournemouth, England
"If you're depressed in the morning then this is what to do. Have a warm shower, eat a big breakfast and when you see someone that you know talk to them like you haven't seen them for ages."
Mollie, 11, Surrey, England
"Write a diary to get rid any bad feelings out of your system, you can then make room for the happiness!!"
Emily, 15, Cambridge, England
"Been down in the dumps for a wee while. Until my wonderful best friend, who is just the funniest person ever, came along and she does know how to make me laugh! Also you should keep a book of all the memories and funny pictures that make you laugh and look back at them - guaranteed to make you smile!!"
Siobhan, 11, Glasgow, Scotland
"Hmmm... being with my friends and family. I try to smile, watch something funny and listen and dance! (even if you can't)"
Hana, 11, Middlesex, England
"Give yourself a makeover, go to the shops and buy your favourite magazine and then watch your favourite movie."
Sophia, 12, Bristol, England
"Monday was great for me! My tips are to snuggle up with a book or a film and hot cocoa and hang out with your friends."
James, 11, Stockton-on-Tees, England
"Laughs + smiles always work!"
Demi-Marie, 15, London, England
"Being with friends and family and the people you love can make you happy."
Sophie, 13, Cardiff, Wales
"If you need to be happy just go to a happy place."
Bethany, 11, Barnsley, England
"I think what makes me smile is listening to my fave songs or watching something funny. You could hang out with friends as well."
Maddie, 13, London, England
"Blue Monday? I had a WONDERFUL day today, all I did was laugh. Laughter is the best medicine!"
Agne, 10, London, England
"Abbie and Kate, my best ever friends, make me happy!"
Amelia, 9, Hampshire, England
"I like making my friends laugh."
Lauren, 9, Rochester, England
"Go to your mates to have a laugh! I had a really nice Monday! I played netball and cycling proficiency, so I found it quite nice."
Kathy, 11, England
"Just do something you really like and think of something happy!"
Anett, 11, London, England
"Eat some coloured veg - it really helps the winter blues - and take small breaks from homework."
Tara, 13, Southampton, England
"Just watch comedies every day!"
Benjamin, 9, Nottingham, England
"Listening to music and hanging out with my friends and sister makes me happy. Also, reading makes me happy."
Hinna, 12, Surrey, England
"My tip is... Make your friends laugh and it will make you happy. Or laugh when they tell a joke. At school today I had a great time because me and my friend were just laughing and laughing and it really brightened my day up!!!!!!"
Claudia, 11, Slough, England
"If you're feeling sad or unhappy, do something that puts a smile on your face, whether it's meeting up with friends, watching your fave film or eating chocolate and try to forget about whatever made you sad."
Erin, 12, Essex, England
"Laughter is the key to happiness!"
Becki, 14, Manchester, England
"Hang around with your friends and have fun."
Rebecca, 11, Southend-on-Sea, England
"If I'm ever upset I have a laugh with anyone who I know who's around me - like friends or family. Maybe even watching something funny or just letting out what I'm sad about to someone I trust, like mum, dad, sister/brother, family member, friends or even a teacher!!"
Mollie, 10, Merseyside, England
"Laugh, smile, be with your friends, they will be able to cheer you up and do something you enjoy. I would listen to music and do sport!!"
Hannah, 12, Scotland
"Today is my birthday so I'm happy and if I'm not my friends cheer me in up seconds!"
Hollie, 13, Nottingham, England
"My friends are always there to give me a laugh and just them being there warms up my day!"
Polly, 10, London, UK
"Friends, family and pets all make me smile. Also, the message boards and some chocolate do too!"
Rosie, 11, Manchester, England
"Sitting with my mum on the sofa and watching a good film!"
Olivia, 9, Hampshire, England
"When you are upset, think of something that makes you smile! It works for me!"
Kyra, 11, Glasgow, Scotland
"I had a good day because there was NO SCHOOL! Yay! But I had homework still to do which was bad!"
Emmi, 11, Prague, Czech Republic
"I am happy because my friends always make me laugh and I have great fun with them!!"
Razia, 11, Birmingham, England
"Friends are the key to happiness!!!!!"
Lindsey, 13, Newcastle, England
"One of my best tips is to think of something you like... like chocolate or your fave TV program. Mine's Top Gear and that always cheers me up."
Rebecca, 11, Manchester, England
"My top tip is always remember the complements you get and forget the rude remarks!"
Abigail, 11, Essex, England
"When I'm sad or miserable I pull faces at friends so they do it back because it makes me laugh."
Connor, 12, Stoke-on-Trent, England
"My friends make me happy all the time. You can tell them lots of important stuff that you can't tell anyone else."
Anisah, 10, Edinburgh, Scotland
"Here, where I live, it's warm enough to swim! So I'm happy that I am able to swim in the middle of January! Plus, it's nice and sunny, and warm outside."
Hayley, 12, Pleasanton, USA
"I find music helps, it brightens up my mood and makes me forget my worries."
Bethan, 14, Gloucester, England
"I have been quite happy today since it's my half-cousin's birthday."
Tom, 12, Newcastle, England
"Whenever I feel sad, I usually go on YouTube and watch videos. They always make me laugh and cheer me up."
Ray, 12, Birmingham, England
"I'm never really happy here! It's actually snowing in Dundee and I'm still not happy."
Kieran, 8, Dundee, Scotland
"I am happy today because my friend told me a big secret and trusts me not to tell anyone."
Sophie, 7, Luton, England
"Smile and SING. My best tip though is to think of Fernando Torres!"
Connie, 13, Cheltenham, England
Lucy, 13, Aylesbury, England
"I'm happy when I see all my best mates and play with them!!!!!"
Eliza, 11, Barwell, England
"Smile. Be friendly. Dance (even if you can't). Sing. Sports. Read happy books. Ignore your enemies."
Penelope and Pricilla, 10, Neath, Wales
"What's to be sad about???!! Here in Preston it's been snowing all afternoon - I'm sooo happy!!!!!"
Rafiah, 12, Preston, England
"Actually today has been a good day; NO homework! But some of my friends didn't have the best day!"
Elisabeth, 11, England
"Always smile, because that makes other people happy too. Do something you enjoy and that is relaxing."
Jasmine, 12, UK
"I am happiest when I am at Guides or drama or cuddling up with my mum on the sofa."
Becky, 10, Scotland
"I'm soooooooooo happy, I talked to the girl of my dreams today woop woop!"
Damien, 12, West Yorkshire, England
"My friends put a smile on my face but not as much as my dog Noah."
Matthew, 13, Gateshead, England
"I think... 1. Always smile through bad things, if you smile you feel much happier. 2. Ignore people if they are mean to you. They are the ones being mean, not you. Also taking a long bath is relaxing."
Georgia, 10, Kent, England
"Have no school!"
Lark, 10, Portsmouth, England
"Talk to friends."
Mickayla, 11, Walsall, England
"Well, Blue Monday does make you sad. I have a sore throat so I'm not going to school."
Zarghona, 9, Barnsley, England
"I love being with my best friends and having a good laugh. I love going shopping, cinema and sleepovers, they make me really happy!!!!"
Andrea, 12, Croydon, England
"I love seeing my best friends in school and I'm happy when I see my girlfriend."
Jordan, 14, London, England
"I think that I'm happiest when I see my best friends. I tell them everything. I tell them most stuff that I don't tell my parents! Plus, never fake happiness - there's no need to!"