If you haven't had your hormones checked -
do it. Find a GOOD doctor though - most don't understand hormones.
I suffered from the same problems and found out I had low Testosterone. Now, I give myself shots, use a CPAP, went lo-carb/high fat, and lift a lot of heavy weights. I'm in the best shape of my life at 46. At 40, I thought I was accelerating towards death - nothing I did mattered. Felt down, always tired, listless, lowered libido, etc. etc. People say I actually look younger today than I did 10 years ago; no joke.
Guys have hormone issues just like women do, it's just not often talked about and when it is it is often misunderstood.
If your hormones are out of whack, nothing you do will compensate.