"I can sleep when I'm dead, but I can't workout when I'm dead...hopefully." 

"If I work out, I can eat my feelings in chocolate and not feel shitty while I'm doing it."

"I won't stay long. 20 minutes of cardio and that's it."

"The gym has good looking men and there's a chance, one of those good looking men could ask me out."

"I refuse to be the fattest friend in my group. Let's do this!"

"I should probably burn off the calories I consumed this weekend drinking wine."

"I won't be as bitchy after I finish working out."