If i'm starting to exercise again, how slow should i start off?

Well, i haven’t been exercising since middle of August. I want to start off slow, but how intense should i start out with and for how long? When should i increase?

I used to jog about 40 mins everyday, and every other day i would do a ab workout and some knee strengthening and arm stuff, right now I want to keep it simple and maybe just use that “torso track” that my mom bought for herself a couple years ago. I feel too lazy now with school and senior year and all, but still want to continue exercising. So how long should i use the torso track for/ how many times a week/ when to increase the time and intensity?