Kristen and her boyfriend go for an afternoon run.
When no one is looking they settle on a park bench.
He pulls down her gym shorts and starts fingering her until she's wet. Then he can't resist her taste and moves his tongue over her sensitive parts. She has an orgasm from the stimulation and excitement of being outdoors and pumped from the workout.
He turns her over and enters her from behind (literally).
It's always a good idea to workout together...
P.S. If you don't like anal, then skip the end (you can still watch the first part).
P.P.S. I find nothing wrong with anal when done properly, but everyone is welcome to their opinions.