Exhausted is a feeling, not a grade
A session can end with your shirt soaked, your legs heavy, and no room for another thought. That can be a hard session. It is not, on its own, proof that it was the right amount of work for you today.
A more useful check is specific: did you practice the movement you planned, at a level that challenged you, and leave enough room to come back to training? Those answers are less dramatic than exhaustion. They are also easier to compare from one session to the next.
This does not mean every workout should feel easy. Resistance training needs effort. ACSM’s current guidance describes several workable ways to build strength and muscle, and does not make feeling destroyed after each session the target. [1]
Separate a hard set from a hard day
One challenging set and an all-out day are different things. You might make a push-up variation difficult enough that the last repetitions need attention, then stop before every other part of the session turns into a fight. Or you might choose an easier variation because sleep, soreness, time, or concentration are not there today.
Neither choice needs a moral label. Record what you actually did: the variation, repetitions or time, and a short note about how demanding it felt. That gives you a reference next time. It does not turn one tired day into a verdict about your discipline.
If the aim is to practice a movement, leaving with a little capacity can be useful. If the aim is a particularly demanding session, name that before you start. Do not let the feeling at the finish decide afterward what the plan was supposed to be.
Use the next session as part of the answer
Before the next planned session, look back at the last one. Could you repeat the movement with control? Were you avoiding it because you expected another punishment? Did you need more recovery than you expected? These are observations, not a diagnosis or a rule for everyone.
Try one small experiment: for two comparable sessions, keep the exercise and setup similar. After each, write one sentence about effort and one about whether you would be willing to do it again in a few days. The notes will not prove the best program. They can show whether “exhausted” is helping you choose, or only making the work harder to repeat.
Stop and seek appropriate medical advice for chest pain, fainting, severe shortness of breath, or symptoms that concern you. For ordinary training decisions, make the next session a little more legible instead of chasing a feeling that disappears by tomorrow.