From Mere Christianity by C.S. Lewis:
“Good and evil both increase at compound interest. That is why the little decisions you and I make every day are of such infinite importance. The smallest good act today is the capture of a strategic point from which, a few months later, you may be able to go on to victories you never dreamed of.
“An apparently trivial indulgence in lust or anger today is the loss of a ridge or railway line or bridgehead from which the enemy may launch an attack otherwise impossible.”
I love how Lewis puts things. He leaves no doubt of the importance of our each and every decision – no matter how small it may seem to us.