I find the liner hurts more than the shading. I get some kind of rush from it, but it is difficult to explain to people who aren't pretty heavily tattooed. I've sat for about five hours in the past. It get worse and worse as the time passes after about the third hour.
Come talk to me after you've done more than 15 minutes. That's nothing. My Mom has done that, and she's in her 70s. Haha.
Ditch whoever told you the lifework was bad. It's not perfect, but there is no such thing as a perfect tattoo. That's a real dick move, trying to ruin your tattoo for you. Enjoy your tattoo, it looks fine.