Instead, success in yoga comes by learning how to be "present" when you practice. You learn to enjoy and respect your body for where it is at the moment and not where you wish it could, or should be (which is living in the future). And success is impeded when you want your body to respond as it did when you were younger (which is living in the past). With a successful yoga practice, you don't need to be anything, such as flexible or strong or even healthy. You just need to pay attention to "the way things are" and just do it (living in and enjoying the present). In so doing, when you learn how to move through life without forcing or making unreasonable goals, and as you move forward paying attention as you go; you will experience the pure joy of the moment. Therefore, by treating your yoga exercises intelligently and respectfully, you move toward balance of body, mind and spirit.
And because the body and mind are so intricately interrelated; as goes your body, goes your mind. Over time, as your body becomes increasingly balanced, and as you increase your flexibility and strength; your awareness and control increases, both physically and emotionally. Likewise, success and joy in relationships comes not through force or manipulation, but from the sheer delight of paying attention to your partner or friend or child or parent and by enjoying their very perfection.