Running is just controlled falling — you lean forward and catch yourself with each step. Your posture is upright from your ankles, not bent at the waist. Your arms swing forward and back, not across your body. Your cadence should be quick enough that you're not overstriding; aim to land closer to underneath your body than in front of it. Breathe through your nose and mouth at easy paces; at hard effort, your breathing will be heavy and fast. Your legs should feel like they're working, but not crushing.