|Homemade swim band - a piece of old inner tube.|
Two: when I get tired I don't activate my abs, and my overall body position suffers a bit. The band is a great reminder to use those abs as if I don't, my legs really drag uselessly behind me!
Using a band is also a great way to turn a swim session into strength training. Slip the band around your ankles, put on some paddles, and you have a bicep/tricep/lat/core strength workout! Great for when you have tired legs but still want to get a good swim in.