The new exercise guidelines [0] recommend getting cardio exercise at moderate intensity. The question is what is moderate intensity for you - how do you find it and measure it? Well, Dr. Margolis, over at Yahoo Health [1] has provided three ways to determine your intensity level.

• The talk test. If you can hold an amiable conversation, then you are not working in the moderate intensity zone. You need to be breathing hard to be in this zone so a normal conversation should not be possible. Run by yourself? Then try singing with your playlist and if you can belt the entire chorus, you need to pick up the pace.
• The "8 to 20" scale. Imagine a scale of intensity between 8 ad 20, with 8 being barely moving (like holding your toddler's hand while he or she navigates the early stages of walking) and 20 being working as hard as 007 in the "parkour/free running" [1] scene in Casino Royale [2]. You want to workout at and be able to maintain intensity of around 12.
• Heart rate. Moderate-intensity exercise means working between 50 and 70 percent of your maximum heart rate. Check out the Fit Calculator [3] to determine your numbers. You want to be work in the Endurance Training Mode - "going the distance."

Writing about all this makes me want to go for a run or a ride! See ya later!

Source [4]