Considering Testosterone Replacement Therapy (TRT)? First ask yourself if you're doing these:
1) ZINC. If you are not deficient in zinc, taking a supplement will not raise your T. However, most men in the USA (and Western Civ generally) are deficient in zinc. You need zinc to make T, and zinc inhibits the activity of the enzyme (aromatase) that converts T into estrogen.
Total intake of zinc, from food and supplements combined, should be less than 100 mg per day. Most men will not get any further benefit beyond about 50 mg per day from food and supps combined. If you take a supp, have it between dinner and bed.
2) LIFT. Forget "cardio" forever. You do need to walk a few hours a week, but it should be slow and low-stress, to work food around the corners of your intestines. It's not about burning calories.
You must lift weights at least one day per week (but never two days in a row - recovery's where you make your gains). Your T "serum level" (the amount in you blood) drops post-workout, because your muscles used T to do the work, now suck T out of blood to replenish, your pituitary gland reads the drop in serum T and signals your balls to make more. More muscle = more T.
You can get a great lifting session with just a bodyweight workout. You don't need a "weight set" or a gym membership. (If you like lifting actual iron, or going to the gym, that's fine of course.)
If you are out of shape, start small and increase slowly.
3) PROTEIN. The standard formula for how much protein you need is: your body weight in kilograms is the number of grams of protein you need each day. Normally that's true, but for at least four - and up to 24 - hours after lifting, you should double that rate of intake. Your baseline remains, plus now you temporarily have the additional need of your skeletal muscles recovering from the workout. If you're not going to give your muscles as much protein as they can use, why are you even bothering to lift?!
4) SLEEP. The four basic rules of healthy sleep are: go dim at least a half hour before bed, in bed before midnight, sleep in darkness and quiet, don't get up until after dawn. Chronic sleep deprivation can lower your T.
5) REST. In addition to getting enough sleep each night, you should have at least one day a week of complete rest. Ideally, lift the day before to maximize benefits of both.
6) FAT. The low fat diet has been a disaster. Your body needs dietary fat to function properly, and the fat it needs is saturated (and mono-unsaturated) animal fat, not that "vegetable oil" crap.
You also need naturally saturated organic (the pollution's in the fat) animal fat specifically to make T. (Never eat high carb and high fat at the same meal, of course.)
7) VITAMIN D. For historical reasons this "nutrient" is called a vitamin, but is actually a steroid hormone. You can make it from sunlight, but the UV-B necessary to make vit D is only available in the temperate zone from 10am - 2pm in Summer, 11am - 1pm Spring and Fall, and not in Winter. Also, UV-B is blocked by smog and clouds (but UV-A, which can give you skin cancer, isn't).
8) MAGNESIUM. Most Americans - male and female - are deficient in magnesium. Whereas calcium helps muscles contract, mag helps muscles relax. This can help you get into phase IV, the deepest most restful stage of sleep. As noted, better sleep can boost your T. Limit calcium - from food and supps - to morning and/or afternoon; get mag after dinner.
9) LOSE THE GUT. Abdominal fat manufactures aromatase, the enzyme that converts T into E. Should you go low carb or low fat? It depends...
10) IODINE. You need iodine (and tyrosine) to make thyroid hormone. Most Americans get enough, but if you don't, low thyroid will decrease T. (You also need selenium - just a little, don't go crazy - to convert thyroid hormone into its active form.)
If, after all that, you decide to go ahead with TRT anyway.. still keep doing all 10 of these things, as they will support both health and fitness!