If you enjoy swimming this would be a good alternative. Biking may be tolerable depending on how sensitive your knee pain is? It does help to have someone to workout with. The reason I signed back up for our local YMCA membership is to have opportunities for the group fitness classes. Having a group to workout with is encouraging and very helpful. Try putting an ice pack on your knee 15 minutes every few hours while awake to see if the inflammation will decline. Also anti-inflammatory medication may help.