Enjoy your workout and don't get discouraged by the pull ups. You can always use a chair to get yourself up and then just slowly lower yourself down. You can use your dip station or two chairs and a broomstick. Do whatever works. I used to do pull ups and hanging leg raises off of a wall when I lived in Malta and had no pull up bar. You just have to make it work sometimes. If you don't have the ball, use a chair to put your feet up, and have fun!