[Cthulhu_]

I went to a personal trainer once, the program was effectively 30 minutes of personal training on one day, 30-60 mins of 'on my own' the other, and the trainer gave me an exact schedule to follow. On the days with the trainer, we could rack up the weights and he'd be there all the time. On my own days, I had to go for much safer exercises - dumbbell bench presses instead of the bar - and at a lower weight.

If you want to just train, go for the safe options and a bit more reps. If you want to really break your limits, never not have a spotter. They will allow you to be a bit less safe on the one hand (e.g. bars with max weights) and provide you with motivation on the other. I never pushed past my limits before I had a spotter.