The resistances are Lust, Anger, Greed, etc. (In Yoga, the Doshas) what MMY uses the 'catch-all' phrase 'stress' for. Additionally, Patanjali meant for us to practice not only step 8 or Samadhi/meditation but the ethical virtues as well (steps 1 & 2 Yama and NiYama) in order to achieve this over-all goal of Yoga or Union.
Even MMY himself says in his Gita under Yoga in the appendix that Patanjali meant all limbs of Yoga to be practiced "simultaneously", MMY's words, not mine!
