Imagine two people washing dishes. One splashes water fast and calls it done, good enough. The other washes with care and attention. Which one do you think is going to be good at everything they do when they grow up?
Being vigorous isn't doing something because you're forced to, it's doing it well because you care! Jesus always did everything with excellence: when he multiplied the loaves, when he healed the sick, when he taught, always with all his heart.