Traditionally , there was no age limit. Older people, sickly people , children and even infants fasted.
Cold showers is a good one.
Yes, God punished us for sins of gluttony. You are right, blessed A.
You can be healed by God. Others gave excellent advice. Also, exercise too. Take walks. Take prayer walks with your wife.
Dwelling on the past is not good. I know. Only Jesus heals. (Don’t listen to man only.)