It can be a combination of a fear of missing the weight, looking stupid if they fail, or a fear of getting hurt that keeps them from lifting the weight. I have some personal experience with this, a few months ago I couldn’t lift my 365lb concrete slab. I attribute the failure to a fear of the object, and a lack of confidence in what I was doing. A few weeks ago I carried the same stone for about 4 sets of 80ft each. I was able to do this because I simply envisioned myself as already lifting it, and now I just have to do it again. I didn’t spend a lot of time staring at it, working myself up into a false frenzy, or standing there for 20 seconds with my eyes closed. I just bent down and picked it up.
The longer I stand in front of the weight and telling myself I can do it, the longer I have for doubt and those negative voices to creep in and tell me I can’t do it. If I just walk up to it and pick it up, my problems have been solved. If you have ever seen me smelling an ammonia cap before I deadlift, its because the ammonia feels like a donkey is kicking me in my olfactory bulb, but it also clears my head of any thoughts, leaving me with the only option available: picking it up.
Keep negative thoughts from creeping in but getting rid of the time spent telling yourself you can do it. You know you can do it, so you don’t waste time beforehand working yourself up into an artificial state of confidence beforehand, just get it done. If you fail or look like a jackass if you miss the weight, who cares? If you end up in a “lifting fail compilation” on Youtube, who cares? None of that matters. Fear of failure will keep you from greatness, I promise you that.
Stop dicking around and Pick It Up.