Older people appear better able to control their emotions
Most people get happier as they grow older, studies on people aged up to their mid-90s suggest.
Despite worries about ill health, income, changes in social status and bereavements, later life tends to be a golden age, according to psychologists.
They found older adults generally make the best of the time they have left and have learned to avoid situations that make them feel sad or stressed.
The young should do the same, they told the American Psychological Association.
The UK is an ageing nation - in less than 25 years, one in four people in the UK will be over 65 and the number of over-85s will have doubled.
And it is expected there will be 30,000 people aged over 100 by the year 2030.
According to University of California psychologist Dr Susan Turk Charles, this should make the UK a happier society.
By reviewing the available studies on emotions and ageing she found that mental wellbeing generally improved with age, except for people with dementia-related ill health.
Work carried out by Dr Laura Carstensen, a psychology professor at Stanford University, suggested why this might be the case.
Dr Carstensen asked volunteers ranging in age from 18 to mid-90s to take part in various experiments and keep diaries of their emotional state.
She found the older people were far less likely than the younger to experience persistent negative moods and were more resilient to hearing personal criticism.
They were also much better at controlling and balancing their emotions - a skill that appeared to improve the older they became.
TIPS FOR A HAPPY OLD AGE
Envisage ways to thoroughly enjoy the years ahead and imagine living to a healthy and happy 100
Design your life and daily routines to reinforce this goal
Don't put all your "social" eggs in one basket - invest time outside of your family and career too
Dr Charles explained: "Based on work by Carstensen and her colleagues, we know that older people are increasingly aware that the time they have left in life is growing shorter.
"They want to make the best of it so they avoid engaging in situations that will make them unhappy.
"They have also had more time to learn and understand the intentions of others which helps them to avoid these stressful situations."
Dr Carstensen said the young would do well to start preparing for their old age now.
This includes adopting a healthy daily routine and ensuring some social investment is spent outside of the workplace and family home.
Andrew Harrop, head of public policy at Age Concern and Help the Aged, said the findings were encouraging.
"For many people, older age and later life is often looked upon with dread and worry.
HAVE YOUR SAY
As you get older you can get more frustrated and grumpy but more importantly you gain a sense of perspective
John Uriel, Wallasey
"Far too many younger people assume that getting older is a process that will inevitably mean sickness, frailty and lack of mobility and greater dependence. However, this is far from the truth in very many cases.
"Many older people lead active, healthy lives enriched by experience and learning.
"This positive advantage can be brought to bear across so many aspects of daily life which - in turn - hugely benefits our ageing society.
"It's vital that there is growing acceptance that just because someone is getting older, it doesn't mean they no longer have a significant contribution to make.
"This study is one of many which shows that later life can be a enormously positive experience."