Someone just told me about the epiphany he experienced in his Christian life when, looking idly down at the top of a Cheerios box while getting breakfast, his attention was suddenly seized by these simple words:
Must be present to win.
It seems to me that that is the simple thing that God asks of us: be present to Me. Pray, and when you do, trust Me enough not to dwell on the past or worry about what might happen tomorrow. Just be here with Me now.