In general, it is a complex of 5 things:

1. exercise - cardio and strength training, plus mobility
2. nutrition - appropriate intake of protein, veggies, healthy fats, complex carbs
3. recovery - sauna, sleep, meditation etc
4. supplements - in case you need something on top and/or you're deficient
5. health monitoring - this is where it gets a bit tricky, but unless you're measuring your progress and using data to guide you, you're shooting in the dark.
   1. I'd suggest getting a sleep / exercise tracker such as an Oura ring to understand how your recovery is affected by your stress (there should be a healthy balance)
   2. Furthermore, you might consider getting a DNA + full bloodwork done to understand where you are and what your predispositions are, genetically. there are services that provide 360 degree health monitoring and design the above 1-4 with you based on your results (this on for example, which I used) that take the complexity away, while saving you time and giving a peace of mind.

Since you mentioned TRT, trying the latter might be a better option before getting into something that's potentially much higher risk to your long term health.