Arjuna:
What is the force that binds us to selfish
deeds, O Krishna?  What power moves us
even against our will, as if forcing us?

Krishna:
It is selfish desire and anger, arising from
the guna of rajas;  these are the appetites and
evils which threaten a person in this life.

Anger and egotism can get us to do things that we think are for our benefit but, in the long term, are not.  They may in fact be harming us.  The ego especially doesn't want us to become spiritual because it feels threatened by it.  This doesn't mean, as some popular spiritual writers claim, that the ego needs to be destroyed, but it does need to be controlled.  And action when we are angry is rarely to the benefit of us or others.