How do i train myself to sit like L? (death note)?

I have decided to be like L, becouse i love him, and i want to be the best L i can, i know fangirl weirdness, but, i also like to cosplay, but anyway, i really need to know what are the best things i can do to train my legs to get used to that, and eventually be able to sit like L for a very long time, and doing things like jumping on the trampoline and riding a bike a lot, would those kind of things help out to strengthen my legs?