Swimmer Kerri-Anne is a British twice record holder.
Here she explains what it's like competing in big competitions like this weekend's European Junior Championships - and how she trains for them
"I've been competing in the European Junior Championships - where top junior swimmers from all over Europe get together for a massive competition.
So far I've come second in the four by 200m Relay, second in the 800m Freestyle and I took bronze in the 400m Freestyle.
Some of the races are run as a straight final - meaning there is only one heat - and in others you have to do well in the heats running up to the final to be in with a chance of winning.
I've been swimming since I was four and I hold two British Junior records in the 800m freestyle short course and the 1500m.
I have to be dedicated when I practise because I compete in distance swimming. I practise at least every day and do at least ten to eleven sessions a week.
It can be long and boring but it's worth it in the end.
I'd like to turn pro
It can also be hard fitting my school work around swimming. But I've just finished my GCSEs and am about to start my A Levels so I manage.