Don't waste life in doubts and fears; spend yourself on the work before you, well assured that the right performance of this hour's duties will be the best preparation for the hours and ages that will follow it.
I'm not sure who said this, but it seems helpful as an approach to the mysteries of life and work. It seems to reflect a kind of trust that is needed to move, in spite of uncertainties that we often feel. Something is gained (learning, etc.) in the doing of things, especially when under-girded with at sense of faith. And, the things gained are not necessarily tied to success.
