These two pull against each other more than the sentence admits. Wanting more is how anything gets built; being satisfied is how anything gets enjoyed. Lean too far either way and you get a restless person who never arrives, or a comfortable one who stops.
The workable arrangement is less about balance than timing. Ambition during working hours. Satisfaction in the evening, deliberately, with the striving set down for the night.
Most people run one setting all day and wonder why they're tired.
Tonight, when you stop, actually stop. Whatever isn't finished will still be unfinished at nine tomorrow.