22.Krsna inspires confidence in this verse by giving His own example. This verse speaks to the devotional as well as the intellectual. The devotee sees that Krsna had no stake in the battle yet as Arjuna’s charioteer He was in the middle of it all. The intellectual views Krsna as Atman. Atman has no interest in any activity yet nothing can happen without Atman.
As long as you have vasanas you have no choice but to act. Krsna was born Realised and had no vasanas but was active right through life. As the Pandavas’ ambassador He tried to negotiate peace with Duryodhana. He helped Arjuna elope with Subhadra when Duryodhana was trying to take her away from him. He protected people and fought evil even as a child. And He entertained and amused everyone with his pranks! Krsna was the mischievous yet endearing One who captivated the Gopis and beckoned them to the Higher.
The three worlds are heaven, earth and hell. Philosophically they represent the waking, dream and deep sleep states that we go through.
23. Krsna instills fear by saying that everyone will become inactive if He stopped acting. That would be disastrous.This is a purely emotional angle that works with Arjuna. An intellectual person would not have responded to it.
‘I work tirelessly’. Fatigue comes from selfishness. A child is energetic because of its unselfishness. Mental stress drains you of vitality.