The exercises; Push ups
Lie on the floor, push yourself up. A lot. It is difficult at first but keep your heels, ass and shoulders in a straight line by tensing your abs.
Again, do as many as you can in a minute, even if at first it's only 1. Like chin ups the early progression of strength is very fast,
just keep pushing yourself for a couple of minutes every day and you'll get up to sets of 20+ in no time.
Grips; vary between thumbs together underneath you, to under your nipples, to under your shoulders, to wide-grip press ups.
All these variations just make sure you get all the different muscles, and they can be mentally refreshing to a tough workout.
EASY VERSION- push- downs, quite self-explanatory, just lower yourself in a pressup position as slowly as you can and you'll feel the burn.
Continue until you have the strength to do your first real push up and you're away on the curve.
Again just a minute per day will get you results, to do more have a minute or two's rest then do another intense minute. Listen to your body.
This will improve your; neck, shoulders, back, chest, triceps, forearms, wrists, lats, abs, and hip flexors.
Note that between this and chin ups you are covering all major upper body muscle groups with just two body weight exercises.
Again, the infinite gains rule applies because all the muscle you pile on will be contributing to your weight, and thus the weight you make yourself lift.
Final post, running.
Run on your toes. ALWAYS.
If you're going on your first ever run, I don't care how slow you are, YOU KEEP ON THOSE TOES AS A PRIORITY.
This forces your calf muscles to make massive gains because they're taking all your weight and springing it back upwards.
This is insanely good for them, mine now get noticed by girls as a thing. We're built to run this way.
(Fun fact, in medieval-industrial revolution Britain calf muscles were considered the sexy muscles, over biceps and abs. That's why they wore those weird white calf socks to show off)
As long as you follow the toes rule you can't go too wrong with running, as long as you push yourself to come back from every run sweating and panting.
As you get fitter you'll feel the wind under your wings and start to enjoy running, it gives one a good sense of freedom.
At this point you'll want to start running with more power and speed, which is when you'll start building up your quads (massive thighs inbound).
Running will also de-fat you, before too long you'll see those abs shining through- they get worked by running too, as well as the hip flexors.
After a good bit of running your whole body will feel like a coiled spring ready to catapult you over the ground. You'll marvel at your biology for sure, after all humans are the best running species.
For completion, running improves your; ankles, calfs, quads, glutes (ass), hip flexors, abs, neck, shoulders and forearms.
To conclude, with these three exercises anyone can get /fit/ as winnie the pooh. Just keep pushing yourself at them and the gains will come sooner than you think.
My favourite routine is; run every other day, and do 3 minutes of both chin ups and press ups every day. The beauty is that it's so adaptable.
And finally the most important point
LITTLE and OFTEN is BEST. There's no point thrashing yourself at the gym or anywhere if you can't move for 3 days afterwards (I've made this mistake so you don't have to).
You don't have to workout every day, but 10 minutes 5 days a week is better than half an hour 3 days a week. You've got to keep the ball rolling.