One interesting thing to note is that many people use more force than necessary with their fretting hand. This was certainly true of me. Some hold the guitar neck with some sort of death-grip.
One useful exercise is to fret a note as you normally do, and play it. Then keep picking or plucking that note with gradually less pressure applied by your fretting fingers. At some point, the note will choke and not sound out any more. Then, a little more pressure can be applied to make it sound out again. That minimal level of force is going to be the ideal amount for stamina and to prevent injury. There’s nothing to be gained by pressing harder, in fact you can bend notes slightly sharp by pressing really hard. In many forms of instrument practice, hand tension is often the enemy (especially for faster soloing).
One useful exercise is to fret a note as you normally do, and play it. Then keep picking or plucking that note with gradually less pressure applied by your fretting fingers. At some point, the note will choke and not sound out any more. Then, a little more pressure can be applied to make it sound out again. That minimal level of force is going to be the ideal amount for stamina and to prevent injury. There’s nothing to be gained by pressing harder, in fact you can bend notes slightly sharp by pressing really hard. In many forms of instrument practice, hand tension is often the enemy (especially for faster soloing).