It looks easy but it is hard! Try doing planks for 30-60 seconds a day. After a week, try to increase your time!
Planks and burpees are my favorite exercises because they work so many parts of your body. Planks are an awesome test of endurance, and you feel them in your arms, shoulders, and core.
You can do variations of planks: on your elbows, on your hands (pushup position), one armed side planks, reverse upside down planks, the possibilities are endless!