First, young athletes need to get their hearts and lungs back into shape by performing regular cardiovascular exercise. There are lots of options out there for cardio, but since they will be playing basketball the best option would be to push, preferably in their sports chair, for at least 30 minutes, three days a week. Twice a week they should be doing a sprint routine, in which they may be instructed to complete different-length sprints. For example, if on a basketball court, they can sprint multiple distances from as short as baseline to foul line, all the way up to baseline-to-baseline and back.  In the beginning, if needed, let them rest for twice the amount of time it takes them to do the sprint. For example, if the sprint takes them 30 seconds, allow them to rest for one minute before they start their next sprint. As your child continues to exercise and improve, you should start to decrease that rest time until he or she is able to do back-to-back sprints.