Start working out.
First couple weeks are a drag but after that you'll notice how much benefit it makes to both your physical and mental health.
10 minutes at a time few times a day.
Take a rest day when you feel like you need to, calisthetics, just use your own bodyweight, basic stuff. Pullups squats dips, little bit of cardio.
It changed my life, I was never unfit or overweight but used to be very sedentary outside of working, just working out and getting a good mattress, completely changed my life.
Don't forget to stretch