The hardest thing in the world is to do.
To do your work.
To get up and get that workout done.
To work with 101% honesty.
To be honest even when no one is watching you.
To not make fun of others. (There is a very visible line between making fun of others and having fun with others.)
To sleep on time.
To turn off internet.
To cook your food yourself.
But you know what?
Not doing all of these is harder.