I'm doing pull ups on the local elementary school's monkey bars (we don't have a pullup bar in our house), and I'm getting blisters that I keep rubbing when I do the pull ups. They're extremely painful and one broke today. Not to mention, it's making my grip weaker because it hurts. Any suggestions to circumvent this problem? Also, the monkey bars are thinner than regular pull up bars, so I'm worried I may not be able to get as many pull ups when I actually get to the Academy (I might have a weaker grip with a larger bar).