There are multiple reasons people blast and cruise (cruise being at a TRT dose). The main one for me is the myriad environmental/lifestyle factors which can impact your test levels. Since I have been on a TRT dose (since some time in March following a 12 week test e/primo cycle), I feel much more 'level' on a consistent basis. A lot less days where I have to force myself to shuffle into the gym and get some work done due to lack of energy or motivation. I feel better all around, better mood, etc. I never had my levels tested prior to this, but once I get home in a month or two I am going to have my T levels checked while cruising to see where I am at (guessing mid- to high-normal).
Speaking of which, if you can afford the testing (or if your insurance will cover it) I would recommend getting your T tested, regardless of your age. Even for active, weight training gym rats who look like the model of manliness, there is a good chance you are running low. Friend of mine was that type, late 20s (I think, might be mid 20s), Adonis fitness model physique, trained CF and Olympic lifting (USAW Level 1 coach, so he actually has a clue, and isn't a total koolaid drinker when it comes to CF). Great build, ridiculous physical condition, etc. Started dragging, got tested, came in at a whopping 200. In his article the other day (yesterday?), TC referenced research showing that healthy weight lifter/bodybuilder types are more susceptible to low T than our sedentary brothers.