YS I 21: tiivra-saMvegaanaam aasannaH
Taimni: It (samaadhi) is nearest to those whose desire is intensely strong. Somehow I get the impression that Patañjali suggests samaadhi would be "easiest" for pitta-types. Isn't pitta somehow connected with rajo-guNa, which in turn is associated with (strong) desire (kaama) and intensity in general? Heck, why would the bigwigs of TMO otherwise be called 'raja-s'?? ;D