Jogging, walking, race-walking, exercising at home (I use books with callisthenics and weight bearing exercises) are all free. Books can be found low cost at bookstores or used bookstores and even
on eBay. A jumprope is a helpful way to get QUICK cardio exercise, but work up slowly. Using your arms and legs during arm circles leg lifts provides weight "resistance" training without investing in dumbells.