Here are terrific fitness tips to incorporate into your workout routines.

Fitness tips # 1. Step on the gas. Alternate the speed and intensity of any cardio workout routines. For instance, if you're walking, do a few minutes at a moderate pace, then speed-walk or jog for a few minutes; repeat. If you're running, go for a few minutes, then sprint for a minute and repeat. Do the same with cycling, inline skating, swimming or any activity of your choice.

Fitness tips # 2. Go for a bonus. Do an extra 15-20 minutes of your cardio workout routines in addition to and apart from your regular aerobic workout. For example, if you usually go to the gym after work, wake up 20 minutes earlier and head outside for a brisk morning walk, hike or bike ride in your neighborhood; it'll be an energizing change of pace. (Just remember to warm up as always; high-intensity exercise early in the morning when your body temperature is still low can lead to injury.)

Fitness tips # 3. Add some muscle. Incorporate some strengthening and toning exercises into your walks or runs: Do shuffles, step-ups, high-knee jogs or other exercises (see # 5 below) at the end of every fourth block or quarter-mile.

Fitness tips # 4. Take to the hills. Hike an uphill trail or climb stairs to add intensity and work muscles in a different way. Do the Side Squat up and down a hill, for example.

Now check out the plyometric exercises that can give your cardio a quick and powerful boost!