90 DAY PLANK CHALLENGE for beginners/intermediate! I wouldn't call this intermediate; I've been planking less than a month and I'm already ahead of where they have you at 90 days. But this is great for just starting out!
What if everybody ran? Athletic apparel company Mizuno partnered with scientists at the University of North Carolina to find out what a nation of runners might look like, and the results are pretty incredible! Food for thought.