How hard is a 300 yard swim?

I know lifeguards in their 50's and 60's so this really isn't that hard once you get your stamina up. There's no trick to not running out of breath easily. You just have to be swimming at *least* 500 yards every other day as fast as you can. That will build endurance. As odd as it sounds, you need more weight on you. That weight needs to be muscle though! So you need to swim a lot and use drills to help you build up your strength. For the brick you just use 1 arm sidestroke to bring it back.