Playing the guitar can be a tiring experience due to the excess pressure unnecessarily employed, this needn’t be the case. It is surprising how little pressure is need to fret a note clearly if it is fretted accurately.
I regularly hear from students that they were initially taught to position the LH fingertips in the middle of the frets - a huge amount of pressure is needed to fret here without any buzzes. Crazy. A simple experiment would be to position the fingertip right up to the fret wire, press, sound the note, then release the pressure as much as possible until a buzz appears, then increase the pressure a tiny amount; it really is surprising how much energy can be saved.
The initial stage of releasing the tension and stress usually employed is to do what is known as ‘sloppy practise’ - here the focus is to keep the LH (and therefore RH which echoes whatever the LH does tension wise) tension-free and fingertip position as accurate as possible by not pressing at all. It literally sounds horrendous, but that is irrelevant at this stage. Following much repetition slightly more pressure can be applied, but just a little at a time, over a long period of time.
The benefits of playing without any excess pressure has huge benefits to all our playing: a lack of tension results in more musical playing and much less fatigue.