Same for us, we also do mobility before swimming. We start with breathing deep, Bring awareness to the Moment, then waking up the joints through circles in both directions of every Joint, wrists, shoulders, hip, knee, ankles, followed by rotating Back and forth and tapping. Then active mobility of shoulders, hips and ankles. Then strengthening like planks. Then activation like rope skipping, jumping Jacks, squats, kick boxing moves.