The sand was just warming under my feet last Saturday morning, the ocean breeze cutting across the beach as I walked toward my usual court. I’ve played beach volleyball with the same group (mostly men, a few women) for more than fifteen years. We only play two-on-two (no fours or sixes), and it’s one of my favorite parts of the week. Frustratingly, my skill level changes from week to week, and it took me years to realize that when I focus on just two things—especially when a serve is coming in—everything flows better. Those two things are…