Interval training is one of the best ways to increase cardiovascular endurance and strength. Using intervals will increase your threshold of training. So, to get to the next level (or, to just kick your butt in record time), try adding some intervals to your cardio routine. The most basic interval would be walk-run intervals. If you are usually a walker, try adding a run intervals, either in time (start with 30 second bursts), or distance (One city block at a time). To start this kind of interval, try the program outlined at www.coolrunning.com . The C25K app is also available on Iphone and will guide you through the process.
There are other types of intervals, as well. Do you want to be a swimmer? Start by using the kick board and add a lap of swimming every third lap. Want to challenge yourself on the bike? Try sprint intervals or higher intensity intervals. www.motiontraxx.com has music for bike interval training led by great spinning instructors. Follow the music, and you'll do automatic intervals at set times. Are you a runner and want to increase your strength and time? Short sprint intervals challenge the muscles from a different angle. If you are not ready to sprint, try intervals of a slightly higher rate. A Garmin watch or similar will have times and distances built in so that you can see what your rate is in any given time (www.garmin.com), or use a metronome or metronome app to challenge your pace. For example, if you notice you normally run at a BPM of 160, add some intervals of 180. Start with just 30 second intervals blocked with 3 minutes of your regular speed, and then increase the time of the interval slowly.