If you're guilty of only including cardio in your workouts, then you may want to keep reading. Yes, guilty may not be a great word choice, because any exercise is better than no exercise. However, you may be doing yourself a disservice for not including strength and resistance training into your fitness routine. Here are some smart reasons you should add it to your repertoire.

1. You'll live longer.

According to research from UCLA, the more muscle mass we have, the less likely we are to die prematurely.

2. For better sleep.

Exercise improves sleep. A small study in older men found that resistance training in particular reduced the number of times the participants woke up during the night.

3. To protect your bones.

Weight-bearing exercises and strength training can help increase bone density, which reduces the risk of fractures and breaks.

4. To boost your balance.

Falling is a big cause of bone breaks as we age, and resistance training helps improve your balance.

5. To help your heart.

Resistance training helps lower blood pressure and the American Heart Association recommends adults complete two strength training sessions a week.

6. It can make you happier.

Strength training has been linked to improving mental health, specifically reduced anxiety and depression symptoms. It can also improve your self-esteem.

7. To burn more calories.

More muscles mean you burn more calories, even at rest.

8. It will help you run faster, bike harder, swim longer.

Why? Because you're building stronger and more powerful muscles that will allow you to do just that.

9. You can notice progress quickly.

You can easily set goals with weight amounts and when you exceed them, it's very satisfying. You'll be surprised how quickly you'll find a weight you used to think was heavy to feel lighter.

10. It doesn't take too long.

Around 30-60 minutes a week total is enough, so adding on a little bit at a time after a cardio workout won't take up too much more of your time.

11. You can do it anywhere.

You can use anything as weights - fill jars or bottles with sand, stones, etc. You can use your own bodyweight by doing exercises like squats and pushups.  You can buy a DVD and follow along.

12. To look better in your skinny jeans.

Building muscle can help you burn fat quicker. This means you'll slim down faster than cardio alone.

Great reasons, but where do you start? Your best option would be to consult a physical trainer. If you have any health issues, you should also consult a doctor to make sure resistance training poses no health risks. It's best to ease into it and take it slow to help avoid any injuries.