If you don't feel challenged, it's because you're not doing enough. Ballet should never feel comfortable. Comfortable is lazy! If you're comfortable when you dance, you're not pushing yourself hard enough. 100 % is not enough. You have to give 200%. One tendu takes years of hard work and will never be perfect. Everything in ballet is a challenge.
The truth is cruel, but it can be loved, and it makes free those who have loved it.