There are all sorts of crazy fitness facts floating around out there. Some are things you've heard so many times they just seem like common sense and you don't really think about them. Others seem to be kind of out there, but when you look into them they actually turn out to be helpful tips. Here are 6 of our favorite health facts and some tips on how you can take this fun knowledge and use it to improve your life. 1. Laughing really is Good for you! It's fun so why wouldn't it be? But seriously... laughter has been shown to reduce Cortisol levels. Cortisol is a hormone that is linked to stress which weakens the immune system, increases blood sugar and can negatively effect bone density and the reproductive system. So lighten up, laugh a little... and maybe strengthen your body in the process :) 2. Muscle doesn't technically weigh more than fat... it's just denser! Even though we all say it... we may need to explain it.   Which weighs more?  A pound of rocks or a pound of marshmallows?  The answer, of course, is that they both weigh the same... a pound is a pound. Same thing goes with muscle and fat... the difference is that muscle is more dense, or less volume for the same weight. So if you want to lose inches and tighten up, trade fat for muscle!! :) Added Bonus? Muscle tissue requires more energy from your body than fat; leading to an increase in your metabolism! Conclusion?  To boost your metabolism and change your body composition, it's best to gain lean muscle tone.  Include your toning workouts 4 times a week mixed with cardio 4+ times a week. 3. Sitting = Weight Gain It's common knowledge that it's unhealthy to be a couch potato but it's not just trading a training routine for TV that's hurting you. Sitting actually weakens muscles and burns far fewer calories than standing. Also, since you aren't using your largest muscle groups (legs & core) when sitting your metabolism slows down and makes it harder to burn calories even when you are active.  We know that many of you have to sit a lot at work, so mix it up with some light physical activity every hour or so. Don't let those calories you aren't burning add up!  Try this video for our favorite office workouts! 4. Stretching cold before a workout might not be the best idea... Stretching is important, but there is a lot of misunderstanding about the best ways to do it. You should always warm up before you stretch, stretching cold muscles can increase the risk of injury. Do a quick warm up before stretching pre-workout. For best results stretch thoroughly after your workout to improve blood flow to muscles for quicker recovery and promotes longer, leaner muscle tone.  We like to do 'dynamic stretching' before our workout and the foam roller before & after.  Click here for some dynamic stretching... and here for a video on the foam roller! 5. Exercise Improves Brain Function We all know that exercise has physical benefits, but did you know it's good for your brain? Regular workouts can improve your mood and alertness. It also makes for clearer thought which improves mental performance. Basically, working out is a natural way to stimulate your nervous system! 6. Music Improves Workouts :) We love to listen to music when we workout, but did you know that besides being fun, putting on a playlist can actually make your workout more effective? Research has shown that people who workout to music exercise with more intensity and are less likely to quit the activity early!  This is so true for us... how about you?  What do you like to listen to during your workouts?  Comment below :)   What are your favorite fitness facts? Share in the comments~   Want even more helpful, healthful facts? Try the Tone It Up Nutrition Plan! Visit http://www.toneitupdiet.com/ for more info :)