(Unless you're being a jerk, e.g. hogging equipment)
https://suppversity.blogspot.com/2016/05/not-resting-long-en...
I knew that if I didn't have a monetary consequence and someone holding me accountable, I'd never use the gym membership I paid for.
Even 30minutes walking daily makes a huge difference
http://www.startbodyweight.com/
Planks, push-ups, and squats of many variations require no equipment at all.
Add dip bars and a chin-up bar/rings and you're basically set.
Variations mean people who've never exercised before can start very small and work their way up to incredibly challenging routines.
For cardio, good ol' walking and running work. And if you try running, don't think you have to immediately start running continuously; interval training is a thing, and is a great way to start small and work your way up.
If you absolutely can't do the gym, you can run. You can go to yoga (another place where absolutely no one is judging you or even looking at you except the teacher).