Plank
One exercise that works the entire body
Tightens the core and then do variations
Start with 15 seconds 3 sets
Work your way up to 60 seconds
Tighten your core breath out through the mouth and in through the nose
Take your time.
Play music you love to listen to... It helps you concentrate on your breath and the beat of the music
Start slow
Of course with any exercise regime consult your physician
Blessings