From what i've learnt, the hormonal changes will begins as soon as age reach 55. You can feel energetic but understand that your body is not anymore. But since you're only reaching 40 ish, i was thinking it's only in your head. If there is an issue you should seek for a medical counsel.

ED commonly happen for those 60 above right?. That is correct but not accurate. The actual fact is it can happen in all age and if you ask any doctors working in hospital, the statistical number is quite scary and its increasing year by year. One of the cause of ED is mainly coming from psychosocial perspective (Eg: the mpre you think about it, the more it can actually happen. And also frequent watching cORN - no good man). But i do think there is no major issue with you, maybe it just a normal hormone changes due to boring sedentary lifestyle. Change it you you good to go!. Take a vacation for instant. Then hit the gym or park and eat a good food. Do that with your wife / kids.

Do not afraid to pay a visit to a doctor. No harm done yes?. Err maybe the harm part only will cost you rm5 max for government clinic and rm40 for private clinic