Competitions are all about performance, winning or losing. Yoga is different, it is meant to bring you to the centre. Sometimes you might find yourself comparing yourself to others in the class, but there is no need to compare yourself to the person next to you or your teacher, if you do, your concentration will wander like a stray animal. You will not be centred.
There is no pre-requisite to be flexible in yoga. Many practitioners would love to be flexible. Many yoga students start yoga in old age to work on their flexibility, but there is often misunderstanding. If you are flexible, that is good. If you're not flexible, that's good as well. Give your body your total concentration and work with it as much as it allows. If you are very flexible and you attend a yoga class, there is great temptation to boost your ego by comparing yourself to the other yoga students. But this is the very moment when you reduce a yoga lesson into mere performance. You are demonstrating your ability.
If you are not flexible and you attend a yoga lesson and you work with total concentration on your body, without comparing yourself to others, you will be able to transform an ordinary yoga lesson into a blessing for yourself and your body.
In both cases, work with the focus in mind. Find your way inwards and communicate with your body. You will find yourself diving into the infinity of your potential. This is the essence of YOGA. Translated YOGA means "Union". You will be uniting your mind and body. If your attention is elsewhere, unification has failed. If you turn your mind to your body, you will be in the here and now because your body is always in the here and now. It is only your mind that can prevent you from uniting your body and mind.