I think more to the point, you are going to have to take the shots for the rest of your life, as the testes will shrink and will be unable to restart production ???
It may also interfere with fertility ?
For about two years now, I get a shot by a nurse every two weeks. I haven’t noticed much of a difference in my energy levels, but I have narcolepsy so I don’t know if T would do me much good in that department. I’ve been lifting weights a few times a week for about nine years, I pretty much plateaued a few years in, then once I started T I started making gains again. Nothing magical, but noticeable. No negative side effects that I can tell.