If swimming a few hundred to a thousand yards is considered a decent workout for you and not a warmup, this series of workouts in the pool is right for you. You are also likely not a competitive swimmer and get bored looking at a black line for any amount of time. Here is a workout that features several types of swim skills that you can mix and match and get some great (not boring) non-impact aerobic activity:
All Kinds of Swimming 200m warmup – Any stroke and mix and match. 5 x 100 sprints any stroke. Rest as needed. Rest with treading 1 minute or 1 minute core work on the pool deck (crunches, leg levers, flutterkicks). Try adding pull-outs during the rest set. Basically pulling your body out of the water using the edge of the pool. Shoot for 5-10 pull-outs each set. Kickboard 100m flutterkick 100m scissor kick 100m breast stroke 500m with fins – mix in different strokes from freestyle, side stroke, back stroke (just kicking), and underwater dolphin kicks. 10 minute tread - no hands. Try to mix in different kicks from scissor kick, little flutterkicks, breast stroke kick, and the egg-beater kick.
10 minute cooldown doing dynamic stretches in chest deep water: buttkickers, frankenstein walks, side leg swings, front/back leg swings, high knee lifts, run in place.
If swimming is not your thing, but you can swim and want to change things up with your cardio, give this routine a try. It is one of the best non-impact, full body aerobic activities there is.