How do you survive emotionally in a failed marriage?

Neither of us are cheating, but he has medical issues that hinder some aspects of being together and I am quite frustrated. He has also grown comfortable and content. My heart aches but I can't just up and leave for selfish reasons because we have 2 kids and plus I know he needs someone there to care for him, and I do love him...it's just devolved more into a "room-mate/friend" kind of love. Does anyone have any tips? I am very unhappy. I have taken up a lot of healthy habits to take my mind of my cirstance. I run long distances daily, I push myself until I can't run any further, maybe hoping I'll just die from a heart attack or something...morbid huh? Anyways, yes I've done all I can. But what can I do to remedy this without his 50%? He has a chronic back conditon and would rather sit and watch WWE or NASCAR and drink beer ( and talk about these things) and I'd rather backpack into the mountains and spend the night looking at the stars through the telescope and pondering the universe and talking about the beauty that surrounds us. We have become incompatible. 6 years now...what can I do?