Because I was working the same muscles every day, they began developing to accommodate my routine in the most efficient way. In the same way that a toddler’s muscles develop to walk with grace and ease, my HIIT routines were becoming easier with repetition. Yes, efficiency is a good and natural way for our bodies to develop, but my strength and mobility had plateaued, and repetitive movements made me prone to injury over time. My muscles were so tight that my sleep suffered and I couldn’t even touch my toes! Even though I was strong enough to pick things up, I wasn’t mobile enough to bend down and reach them. The healthiest and most effective fitness strategies emphasizing diversity, so I added yoga classes into my exercise routine. Yoga increased the range of motion in my joints and stretched my muscles. I sweat hard, even though it was low impact. Instead of losing my breath, I was able to focus on it. It strengthened my joints instead of straining them and I left feeling refreshed. Maintaining this diversity in my exercise routine has broken old exercise patterns enough to reignite muscle development and prevent repetitive stress injuries. Best of all, it gave me more range of motion, making my HIIT workouts both stronger and safer. Diversity is key.