In December of 2014, we spoke with Brian MacKenzie, founder of crossfit endurance, ultrarunner and co-author of "Unbreakable Runner, Unleash the Power of Strength & Conditioning for a Lifetime of Running Strong". He joined The Nation to talk about how you can train for lifelong healthy and sustainable running by incorporating crossfit endurance training. The main principles include:

• Develop correct and efficient running skills
• Build running endurance without injury
• Build functional strength, conditioning and mobility
• Focus on nutrition

Get the book HERE

Brian's other book, " Power Speed ENDURANCE: A Skill-Based Approach to Endurance Training"