I’m almost 50 and for me it was around 42. Injuries started occurring frequently and my sleep pattern began to suffer then as well. ED started to creep up as well. TRT has changed lots of things for the good, but I still “feel” myself slowing down. When I get outta bed in the morning I really feel my age. Stiff and sore as hell. My shoulders are painful and stiff and my calves and Achilles’ tendons feel like they have no elasticity anymore . I’m convinced that throwing around heavy weights all these years hasn’t helped one bit. Sometimes I wish I woulda taken up running and not weights as a younger guy. Sorry for the rant, just had to get that off my chest as I find it more difficult to get up and moving each morning . Don’t get old guys .