Treat everyone with kindness--not because they are kindhearted, but because you are. One of the greatest gifts we can give another is kindness. If someone is in need, lend a helping hand. Don't do it only for the people you like and respect--that's easy--but also for the ones who drive you crazy and those you don't even know. True kindness lies in the act of giving without the expectation of getting something in return.
The reality is that the ones that are hardest to love are often the ones that need love the most.
Don't just love the people that are easy to love. Love Donald Trump (-: Just kidding.
A more realistic objective is to rid yourself of the emotion hate. Hatred for another person does absolutely nothing except cause you unhappiness and make people around you feel uncomfortable and sometimes results in loss of respect because you can't separate your emotions from rational thinking.