I've always seen pain as important for life. We can only feel profound peace and joy if we can contrast it with prior pain.

It's the receipt of life itself. If we haven't suffered, then how do we know we've been alive? Fearing pain is fearing life itself. Loving pain is loving life.

Isn't it the definition of death, the point of eternal bliss. Cessation of pain. Death is when nothing happens. Pain is the opposite.

I've always seen pain and pleasure as intrinsically linked. Buddhists interpret this as, if you want to avoid pain, you also need to avoid pleasure, (since pain will always be more). I agree with the premise, I just don't agree with the solution

A little less deep, it can also be used to drown out emotional pain. I don't see any fault in this as such, but I think this type of usage requires a very attentive master.

I'm a very hyper active guy and my head has always been a very confusing and raging torrent of thoughts and ideas. If I don't work out every single day, I can't function mentally at the capacity I'd like. Working out, if done with any intensity, is pure pain. I need it to at all be able to think coherent thoughts. Pain is the key to my happiness. And I wouldn't call myself submissive by any stretch.