There could be several ways to stay fit even without going to a gym.
You can do some exercises at home even without an equipment. Like jogging in place, jumping jacks, planking, push ups and squats.
You can also use some items or things at home as your tool or equipment. Like going up and down in the stairs and making bucket with water as weights.
You can also do those exercises outdoor. You can go jogging, running and brisk walking. There could also be some park near your area where there are outdoor exercise equipments that you can use for free.
Overall lifestyle also affects being fit and not just doing some exercises. Like having a balance diet and enough rest/sleep.