“In any moment of decision, the best thing you can do is the right thing.”

                       -Theodore Roosevelt

I think what this quote is trying to say is that when you know something is right to choose then you choose it. For example, if there something bad and a something good and you have to pick which one. What are you going to pick the bad one or the good one. If you pick the bad ones then bad things will come to you. Like being unfriendly, mean etc. And if you pick the good ones then good things will come to you.