Almost every problem a beginner hits has a known cause and a simple fix. If something sounds wrong or feels impossible, it's probably one of these — and it's almost never that you "can't do it."
Ninety percent of "I can't do this" is "I'm trying to do it too fast." Slow enough to be perfect, then speed up gradually.
Don't practice a whole song to fix one spot. Loop the exact problem bar until it's automatic.
Guitar rewards consistency over intensity. Daily short practice beats occasional marathons, and calluses and coordination take weeks — that's normal, not failure.