An indispensable gym exercise!

Join the palms of your hands in front of your breasts (as though you were starting a yoga session, elbows must be slightly raised).

Then create a strong pressure with one palm against the other during 5 seconds.

Renew the exercise several times.

You can also muscle your pectorals (yes, yes it works), by leaning your hands against a wall.

Then you must push the wall as though you wished to "move it" during 10 seconds then let go and start again.