It is appropriate then to start with my favorite sutra (1:33):
maitri karuna mudito pekshanam sukha duhkha punya apunya vishayanam bhavanatah chitta prasadanam ||33||
Elsewhere, I've seen this translation in pairs: approach happiness with love; pain with compassion; success with conviviality; and the unvirtuous with indifference.
In a nutshell, approach each type of person or situation with the appropriate response. If you are happy, love yourself. If someone else is happy, love them too. If you feel pain, be compassionate towards yourself. Be compassionate towards others who may be in pain. If you become successful, be friendly. If someone else is successful be friendly towards them (instead of competitive or jealous). And finally, if someone is being a jerk, be indifferent toward that person. Don't get wrapped up in their stuff. If you feel jerky feelings, don't entertain them. Let them go.
A lot of this is about cultivating the right kinds of relationships in your life. Rather than getting jealous or wishing ill on someone who is experiencing more success or happiness, you should be happy for them and love them for that which will in turn let some of that maybe rub off on to you. On the contrary, if someone is negative and treating you negatively, you should ignore them.
I think about this sutra on a daily basis when I bike around the city. It is very easy to get caught up in the honking and aggressiveness out on the road. I have to make a very conscious effort to not react to the negativity out there with more negativity. Instead, I try to ignore the negativity and focus my energy on the positive aspects of the commute. I smile at other bikers and people walking their dogs. I practice compassion by slowing down for the elderly and allowing them to to cross rather than running lights.