To me aparigraha is very closely linked with contentment: being happy with what is, accepting and appreciating our blessings instead of falsely chasing after outer objects that we think will make us happy. When we are greedy we fail to enjoy what we already have because we're too busy chasing after what we don't. It's like buying a bag of apples and leaving it to rot while you go out to chase after more apples.
Aparigraha does not mean that you have no ambition, on the contrary, you draw up the plans of the future yet you do not delay your happiness by creating dependance on the outcome of the future, you choose to be happy and content, now.
If you look at abstention from greed from an energetic point of view, you will find that letting go actually results in getting more. If you look at feng shui for example: letting go of old energies clears out space for new ones. So giving away what you no longer use results in greater abundance being drawn to you. You might have experienced this in the form of relief whenever you cleared out your closet of old things that were only blocking your sight to see what you have. You may have found that you had treasures in there that you forgot about and were able to enjoy them better.
Greed can present itself in the form of hoarding, keeping what you don't need. This is often a habit that is generated from insecurity. You hang on to people or possessions in the hopes that those will secure certain feelings or fulfill certain needs. We cannot let go of control enough to trust that those needs can be fulfilled from within. We hang on to relationships that are destructive because we don't trust that we can attract better ones.
But the problem with holding on to items (or people) because we think they can provide us with a certain feeling or fill a gap (for example the way too small jeans we showed some good time) means that we do not believe we are worthy of receiving a true replacement of that memory or time which suits us better now. When your vibration is that of worthlessness and anxiety the universe in turn reacts exactly in that way by holding off exactly what we are looking for in that un-needed but possessively held on to item.
Be true to yourself, where does greed present itself in your life? What do you not need that you are hanging on to? What do you have in your life that is worth appreciation that you are not enjoying? What can you do to be more content and happier now?