Find a machine, such as the Freedom Trainer, with two ropes where you can attach handles at the end. Slip a barbell through them, with a weight that is doable and yet a challenge. Grab the barbell with hands shoulder-width apart. "Stand" diagonally with your body straight, at a 45-degree angle, and pull the barbell toward you. Hold the barbell steady. Pull yourself toward the barbell. Do four sets of ten repetitions. This is easier for men. Women at first may be able to do four sets of five repetitions.
This is essentially a variation on a bench press or pull up. You are doing it diagonally, which works different muscle fibers.
Disclaimer: None of the above information can be taken as a substitute for advice from a medical professional such as a physician.
My third book, Pocket Guide to Fitness, is available on www.louizapatsis.com, http://www.authorhouse.com, www.bn.com and http://www.amazon.com. If you look up my name on those Web sites, you will find my other books The Boy in a Wheelchair and Life, Work and Play: Poems and Short Stories.