Intervals are a fun and effective way to improve your fitness levels especially your cardio. During interval training periods of rest are combined with periods of work to help your body adjust to a work load. Kind of like sets and reps but with time instead of repetitions. Now the strict definition of interval training according to the National Strength and Conditioning Association (NSCA) is a 1:1 ratio with work and rest intervals being equal and between 3-5 minutes long. This is a very effective training technique, yet is considered advanced and is often more than a beginner is conditioned for. Please know that you can always scale down and that is often the BEST way to build a good foundation. If you can't run for 3 whole minutes try a modified interval. What I often start my clients with is a very short work interval and a much longer rest interval. This allows you to push yourself in an achievable manner. Try this next time you go for your walk mix in some jog steps. 15 seconds of jogging followed by a 2 minute walk is attainable for most people. Still too much? Try 10 seconds jogging and 3 minutes walking. Find an interval that is doable for you! With consistent application you will soon be able to increase your work interval. Remember we are still wanting to maintain those 150 minutes of exercise per week.