"Nah, just your personal trainer." There's a joke in there somewhere about how Grif needs a cleanup crew more than he does a life coach, but Grif has made himself vulnerable enough to take Wash up on his offer for training, and that deserves encouragement, not a slap in the face. Sometimes the low-hanging fruit is better left alone.

"I wasn't kidding about requiring commitment, though. Are you willing to do that?"