That's kind of a spurious argument to make without drawing it out a bit. Exercise doesn't feel good (at first) if you're morbidly obese, but that's because you really need it.

Adverse reactions to therapy might mean that therapy isn't for you. But more commonly, I think it probably means that you don't have the right therapist and / or you have some really heavy, painful shit that you need to deal with but don't want to. Otherwise you wouldn't be having "adverse reactions" to simply sitting in a room with another human to talk about your life.

Everyone is exactly the same. Everyone feels good about exactly the same things, and bad about exactly the same things.

What I just said is clearly ridiculous.

It should not be a surprise that some people don't feel positive about talking about their lives. If you can't imagine it, I'm afraid you may lack imagination.