This can be considered a progression from the 3 months and 13 steps to health, where you established good social, food, rest and walking habits.
Sometimes people will lack access to a gym, or have one around but as beginners be hesitant to go there. In this case, the person can begin with a bodyweight programme. This is only appropriate for people of BMI 18.5-30 (weight in kg divided by height in metres, divided by height in metres); lighter and heavier people both need to talk to their doctor about nutrition, and heavier people will find the movements difficult.
The routine has five movements.
This starts absurdly easy because we want you to establish the habit of exercise. It's no use our telling you to do 100 burpees a day - even if it were any good for you, you simply wouldn't be able to keep it up. You need to start absurdly easy so you can get some momentum and build things up.
In each movement, begin with doing just 1 (and 1 on each side for lunges). Just do 1, rest, then do the next exercise. Next session, do 2. And so on. If at some point you can't do them all in a row, that's fine, just stop, rest, and complete the rest. For example in one session you do 8 pushups from the knees, the 7th and 8th were a bit shaky but you squeezed them out. Next time you come to do 9, and you find you get to 7 and then can't do another. That's fine, just rest a minute or so, then do another 2, now you've done a total of 7, all good.
Continue in this way until you get 15 total reps. Once you can do 15 pushups from the knees, you'll be able to do 1 from the toes. Start those at 1 and build them up. Likewise, once you can do 15 bodyweight rows with your knees bent, you'll be able to do 1 with your legs straight. Start those also at 1 and build them up again as before. Continue progressing otherwise.
So eventually you build up to 30 squats, 15 full pushups, 15 full bodyweight rows, 30 situps, and 15 Bulgarians. That will take you 30 sessions to do. Ideally you'd do this 3 times a week, so it'd all take you 10 weeks. Just do them when you can - you'll probably get it Mon/Tue this week, Sun/Wed/Fri the next, and so on. That's fine. Make sure it's at least 2 times a week though. Once you're at that level you'll find things a bit easier.
Note that along the way to there, you would have done a total of 465 squats, 240 knee and full pushups, 240 knee and full rows, 465 situps and 240 reverse lunges and 240 Bulgarians. You can see how doing these over 30 sessions and 10-13 weeks is going to give you some momentum, strengthwise.
Having built a base of strength with bodyweight movements, you may then wish to progress to a gym with some combination of machines and free weights. But that's another story.