40 yo here. I do believe middle age is difficult for many men. As one poster alluded to earlier, the study showed male happiness was the worst in the 40s and 50s. I believe this is due to perceived success—another recent study shows the number 1 factor **by far** in male happiness is career satisfaction.
In your 40s and 50s, if you’ve achieved conventional success—I speak here of stereotypical Western financial success—, even as your physical strength declines, you feel a deep and abiding satisfaction that you’ve “made it.” If you’ve been unsuccessful, you can really get down on yourself, especially if you see friends or family doing well.
At 60 and above, my theory is guys learn to be more thankful for what they do have, instead of wincing at their shortcomings. They learn it’s all relative, that so much is down to luck, and so many bad things can happen, a wise man just gets down on his knees and gives thanks for any good he has. This is why male happiness gets better after 60.
If you have taken care of yourself physically, mentally, and financially, the gaps between yourself and those who have NOT start to become HUGE between 35-50. I just went to a wedding and folks are looking rough if they slack off; the winners now have second homes, the losers are scraping for rent. The winners are fit and trim, the losers are obese. Etc, etc. Tough but true.
Keep your stomach flat. Do not gain weight. You can NOT eat much after 35. Running is huge for increasing QUALITY of life, not length. I find length of life after 50 to be much more of a crapshoot.
Save and invest aggressively from your 20s. If you haven’t, start today.
Staying slim and rich will do wonders for avoiding depression. So much of the rest of life is out of our control, try your very best to KICK ASZ at what you can. You CAN control your food intake and your savings rate.
I have achieved conventional success, but knowing the male happiness curve, I have tried to accelerate my mindset to the post-60 state I mentioned above. It’s all relative: I’m fit and trim, but not as special as my youth and never a pro. That’s ok. I’m thankful for my health and mobility.
I’m wealthy and comfortable, but no titan of industry and never will be. That’s ok. I’m thankful for my good fortune.
Bad things have happened, including terrible things for both parents and a child. That’s ok. I’m thankful for the strength to meet the challenges the best I can.
Get down on your knees every day from 35-60 and give thanks for what you have, and do your very best to control what you can, and I wager our depression will be much abated.
Good luck to us all.