Friendships need lots of energy and patience to maintain them. Not to mention time too. When your friend needs you, sometimes when things are not going too well on your side, it is often so easy to turn a deaf ear to their pleas. It is especially during these times, that you must find the strength in you to help your friend. And it is during these times that your friendship will be forged and made stronger.
And you must always be happy for their successes, even when things are not going too well on your side. It might be hard to do for some people but it is something that you need to learn. Think about all the sacrifices your friend has made for you and all the times when he or she was happy for you despite his or her own troubles.
Think about all the happy times you all enjoyed and the sad, rough times you all went through together. That should give you sufficient patience to actually be a true friend for them. Remember, true friends are the next best thing to family. They will always be your pillar of support no matter what. Always.