Flexibility w/o Strength = Instability
Stretching can be an important part of a balanced health and performance program. However, to build the resilient body you desire strength training is critical. Often people embark on a stretching program thinking they are in pursuit of flexibility when what they really want is mobility!
Mobility is the ability to move your body through its full range of motion while maintaining muscular control. When you improve flexibility in the absence of strength you leave your body vulnerable to injury. The reason is that you may lack the strength to stabilize your joints through their newly improved ranges of motion.
Think you don't need to worry because you're already strong? Consider this. Strength comes not only from muscular development, but also through coordination of muscular contraction by the central nervous system. It's not just a matter of having strong muscles, but also allowing your body to adapt to change. We need to condition your body to control those muscles throughout each joints new found range. As that range of motion changes so to must your muscular control to make full, effective, and safe use of your joints. Effective ways to accomplish this goal can include proper resistance training, yoga, and Pilates and more.