I've been very interested in parkour for a while now, but I'm also a 17-year-old, 5'2" girl weighing in at 100 lbs. Parkour seems like fabulous incentive to get into peak physical shape and to build self-confidence, but currently my upper-arm strength is pathetic and I can't do a single pullup.

Is there a recommended, gentler way to get into the workout process than the APK workout that would condition for parkour? From what people are saying, focusing on core seems like a good way to go, but other than that I'm clueless. =D