A 20-Minute Boxing Workout to Build Strength and Endurance One short workout can help you build fitness, achieve better balance and even ward off injuries. No punching bag needed. Author: Rachel Fairbank Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to email a link to a friend (Opens in new window)Click to print (Opens in new window)MoreClick to share on LinkedIn (Opens in new window)Click to share on Reddit (Opens in new window)Click to share on Tumblr (Opens in new window)