Enough is never enough

No matter how long I work out each day, and no matter which works I do or how much sweat drips off of me... I am never satisfied. I always "regret" when I lay down to sleep. I never feel like I've done enough. I don't know why I always feel this way; why I am so hard on myself... I have come a long way & I should be happy with myself but I stay mad at myself instead. I set goals that are uncontainable and way out of reach. I overdo it until I'm so sore I can hardly move. I go back & forth in my head about should I quit or not quit?!? I really feel like a basket case these days :(