I didn't have to stretch before doing it before.

Jack knew it was a little bit of muscle strain but being a woman and having a vagina between his legs was still new to him so he made an appointment to see his gynecologist. 

Who confirm to him that it was just a bit of muscle strain and really nothing to worry about before going on to explain to him the importance of staying flexible & limbering up before doing anything strenuous which was the best way of stopping injuries like this from occurring.