Lifting is complicated for the same reason that dating is complicated. Not everyone is starting from the same place. Not everyone will see the same results, in the same time. That is where the complexity arises. People will see others doing better, and try to find shortcuts, or magic panaceas.
Response depends on your proportion of fast twitch muscle fibers. The more you have the better you'll respond. It really is almost effortless for some. It's genetic. If you're predominantly slow twitch it's going to be a fight. You can make progress, but it will come far more slowly and your potential is limited.
You lift incorrectly, you get trauma, injuries, I've seen a guy in a gym lose an eye. I've seem people leaving weights where they shouldn't, others trip over them.
You choose your date poorly, you could get trauma and injury too I guess.
