From Danielle Baron’s article in International Medical News 10 August 18
As with many different health interventions, there is a sweet spot between doing enough of it and doing too much of it. Too little, and it is not effective. Too much and you could cause unexpected negative repercussions. The subject of exercise has been investigated regarding its effect on mental health.
Over 1.2 million USA citizens were asked about their exercise habits and their mental wellbeing between 2011 and 2015 by researchers at the Centers for Disease Control and Prevention.
All exercise types improved mental health but popular team sports were particularly effective in boosting mental health. The optimal duration of exercise was between 30 and 60 minutes a session, three to five times a week.
Sessions of longer than 90 minutes or done more than 23 times a month however, were related to WORSE mental health.
The authors conclude that blanket advice on exercise could be improved by being more specific about the types, durations and frequencies that were more likely to improve mental health and that further studies could be helpful.
Chekroud SR et al. Association between physical exercise and mental health in 1.2 million individuals in the USA between 2011 and 2015: a cross sectional study. Lancet Psychiatry. Published online 8 August 2018. doi: 10.1016/S2215-0366(18)30227-X
My comments: Oh dear! Well, I’ve got the duration right at 40 minutes but I hate team sports (because I’m useless at hand to eye or foot coordination) and I aim to exercise every day, which these researchers considered “excessive”. Maybe the team sports were more beneficial because of the socialisation aspect as well as the physical aspect. Maybe less than 23 times a month made it something to look forward to and a dopamine hit , “I’ve achieved that” rather than a black mark ” I failed to do my exercise session” as I tend to think about it. I can see the downsides of exercise addiction reflected in this piece of research.
Diabetes Diet 
Something tells me, I will never see optimum and certainly I will never be accused of overdoing it.
LikeLiked by 1 person
Maybe you can find something you love? I’m just back from the West Indies and I had a great time snorkelling. Not too energetic. The rum punches afterwards no doubt removed any benefits pretty quick but I certainly enjoyed myself.
LikeLike