One of the best most basic exercises ever is……..the push-up. Yup, if you only could do one upper body exercise you should choose the push-up. You engage your pectorals, biceps, triceps, deltoids and abdominals. The proper technique to push-ups is as important as the exercise itself. Check out this post and video from fitnessmagazine.com.
https://www.fitnessmagazine.com/workout/arms/exercises/how-to-do-a-push-up/