Yes, in the kindest possible way you are being stupid.
You're 29, you've hardly started with your life. Keep yourself healthy and, with some luck, you could live for another 70 years.
You're in your best years now, mine were my make the most of them.
I'm 73 if I needed to lose 4 stone I'd make damn sure it happened. I wouldn't think 'oh well, my life is over I'll just sink into ruination'
I want to be as comfortable in my body as possible. I want my heart to work as well as it can without having to carry extra weight around.
I want to be able to run up the stairs without my knees or ankles hurting.
I want to be able to take my dog for lovely walks without getting out of breath.
I don't want to fill myself up with rubbish, I want the food I eat to keep my body healthy.
And yes, I do want to look slim.
Don't go on some silly faddy diet. Just start eating a sensible sustainable healthy amount of good food. Get some exercise, walking is fine, you don't have to join a gym, and start looking forward.
You have so much life ahead of you.