Social interaction could be key to kick-starting a fitness regime, US research suggests.
After analysing data, including from the US Military Academy, scientists at Kean University recommended social activities that boosted interactions between less- and more-active people.
When the less active interacted with those who exercised regularly, they felt encouraged, the researchers found.
But those who were less social ended up exercising less.
Regular exercise has already been cited as something that improves mental health significantly, with many finding group activity helpful.
There are many ways to combine socialising and exercising, such as:
walking with friends
taking a fitness class
Exercising with a friend requires commitment and accountability, Andre Bates, of Barry's Bootcamp, which holds group exercise classes across the UK, says.
"It's very easy not to go and exercise when you're relying on yourself - but with a friend, you can use each other for motivation to make sure you stick at what you set out to do," he says.
"You can make friends in a group exercise environment - and then if you're not there for your usual 06:00 class on a Monday or Tuesday, they might ask, 'Where are you?' so there's that little bit of guilt that makes sure you're there next time."
Andre says: "Rather than looking at someone as competition, look at them as a benchmark of what you want to be and don't be afraid to ask them about it and see how they got there.
"We're all pushing for the same purpose, whether it's mental improvement, physical improvement, fitness or performance - everyone is here to improve."
Kai Hunter, 25, who lives in Cardiff, started exercising regularly six months ago - after finding motivation from his group of friends.
"Because I work from home, I didn't really get out much - so I started to put on weight and wanted to do something about it as it was affecting my confidence quite a lot," he tells BBC News.
"I asked a few people in my social circle who were into fitness already how they had got into it - and asked for workout routines."
Kai also gained a lot of motivation sharing progress with friends in a group chat.
"All the people around me were always supporting me," he says. "It was good to have that around me and to feel the results myself."