What are the most common mistakes people make in their first year of training?
Programme hopping every three weeks, which prevents the progression that would have produced results. Chasing soreness and novelty instead of tracking load. Doing far too much isolation work and too little of the basic compound movements. Neglecting protein and sleep while optimising workout details. Comparing week four of their own journey to year six of someone else's. And treating a missed week as a failure rather than a normal interruption. Almost none of the first-year problems are about choosing the wrong exercises; they are about consistency and expectations.
Answers
Protein and sleep being neglected while people argue about rep ranges is the whole picture.
Comparing week four to someone's year six is the one that quietly ends the most attempts.
Programme hopping was mine. I ran four programmes in a year and finished none of them.