You'll know when you start feeling like shit. 6 years ago, at age 42, I felt lethargic, depressed and had a sporadic sex drive. Went to my former doctor and he prescribed anti-depressants, which didn't solve anything. Did alot of internet research, and realized it was my test levels. Found a new Dr. who was an HRT guy (and verified my low test), and things got better almost instantly after my I got on TRT. Find an enlightened Dr., get tested, and get on HRT if the numbers bear that out; your biological age is not the critical indicator, your test level is.