What is fitness? The first definition of fitness is: “health”. Health is defined as “the general condition of the body or mind with reference to soundness and vigor: good health; poor health.”

Last week, we posted a story on 10 tips for entrepreneurs to maintain a healthy lifestyle. This weekend, we’ll take an in-depth look on the future of fitness and the companies that are taking us there. As part of a two-week study on the future of fitness, we’ve dug up 9 inspiring videos on health and fitness. These videos range from hilarious to serious, from geeks to jocks, from the past to the present. Enjoy!

1. Nick Crocker: Floss the teeth you want to keep.

What do you want to change about yourself? Inspired by his dentist, who told him “Floss the teeth you want to keep,” Aussie entrepreneur Nick Crocker lays out 10 steps to make change easier in your life. Crocker is currently working on his startup “Sessions” a service to help people be active with others, which is currently in closed Alpha. Think Meetup meets Foursquare for physical activity.

So how do we change ourselves? It turns out there’s a bunch of little hacks that exist to improve your ability to change. Understanding and applying them allows us to improve our ability change in our own lives. As it turns out, this ability has everything to do with the future of the world.

2. Christopher McDougall: Are we born to run?

Watching this TED Talk may convince you to pick up a pair of those funky, webbed running shoes. Christopher McDougall explores the mysteries of the human desire to run. How did running help early humans survive — and what urges from our ancient ancestors spur us on today? At TEDxPennQuarter, McDougall tells the story of the marathoner with a heart of gold, the unlikely ultra-runner, and the hidden tribe in Mexico that runs to live.

3. Laird Hamilton – The greatest big wave surfer to have lived?

Watching Laird Hamilton is pretty much like watching Tarzan surfing. Hamilton is an American big-wave surfer, co-inventor of tow-in surfing, and an occasional fashion and action-sports model. This man has the biggest cojones imaginable, which explains how he snagged wife Gabrielle Reece, a professional volleyball player and stunning model. The two split their time between residences in Maui, Hawaii, and Malibu, California. The following video is an edit with some pretty raunchy music from Laird Hamilton’s film ‘Laird’.

4. Dan Buettner: How to live to be 100+

To find the path to long life and health, Dan Buettner and team study the world’s “Blue Zones,” communities whose elders live with vim and vigor to record-setting age. At TEDxTC, he shares the 9 common diet and lifestyle habits that keep them spry past age 100. Hint: Plant based diets and loving friends will help you reach your centenarian days.

5. Eric Topol: The wireless future of medicine

Just like we monitor our social feeds, in the future we’ll monitor our vital signs. We are at the perfect health storm of connectivity and data aggregation to enable wireless medicine. Eric Topol says we’ll soon use our smartphones to monitor our vital signs and chronic conditions. At TEDMED, he highlights several of the most important wireless devices in medicine’s future — all helping to keep more of us out of hospital beds.

6. Jamie Heywood: PatientsLikeMe.com

“Wouldn’t it be great if the software we used to take care of ourselves was as good as the software we used to make money?”asks PatientsLikeMe.com founder Jamie Heywood, who built website after his brother was diagnosed with ALS. The Heywood brothers discovered that the collective data had enormous power to comfort, explain and predict. PatientsLikeMe is one part social experiment and one part massive data aggregation. In sharing ourselves and our data, we become vulnerable but it’s allowing us to form a human community once again.

7. Ashtanga Yoga in India

This captivating video is of Ashtanga master Steven Green, shot on location in India. It is a life goal of mine to travel to India and spend 3 months practicing with great teachers such as him. I’ve given myself this challenge: As soon as I can do crow pose to headstand to crow pose and then jump back to chaturanga, I’m going. And I’m not that far off…

8. Aimee Mullins: The opportunity of adversity

I have a major girl crush on Aimee Mullins, the world’s hottest cyborg. The athlete, actress and supermodel was born with fibular hemimelia and, as a result, had both of her legs amputated below the knee when she was just a year old. Growing up, her family doctor said she’d never walk. But at the age of 19, she set world records in the 100-meter dash and long jump. Mullins now has 12 pairs of prosthetic legs, which she can pick and choose from depending on the occasion. In this video below, she sets out to redefine the word “Disabled”.

9. Usain Bolt Smashes 3 World Records

Usain Bolt set 3 world records at the 2008 Beijing Summer Olympics. On August 16th 2008, he claimed the title of “World’s Fastest Man” and set the world record in the men’s 100 meter dash at a blistering pace of 9.69 seconds. This beat his own previous world record of 9.72 seconds that he set just a few months earlier in the year. Usain Bolt clearly has made his mark on history with these 3 world records. And at the age of only 22 years old, he may just be getting started.

Bonus: Marianne St-Gelais cheering for Charles Hamelin’s 500m Gold

Charles Hamelin’s girlfriend Marianne St-Gelais is one of the most excited and supportive fans I’ve ever seen. Watching her entire body convulse in excitement over her boyfriend winning the men’s 500m short track gold is so heartwarming. (Even if she does come across as a little bit nuts!)

Double Bonus: Synchronized Walking

After all that inspiration and motivation, it’s time for a little LOL. This video is synchronized swimming meets army training. And perhaps unsurprising, this team of synchronized walkers hails from Japan.

Tip: Turn the volume down.

Did we miss any of your favorite inspiring health and fitness videos? Please share them in the comments!