It's probably our ego or will that says "I WANT THIS", but wants and needs are often confused. I am not saying that as you become more spiritual you'll want for less, but you will probably be able to differentiate between what you want versus what you need.
And it's OK to want stuff. We work hard and a few treats are perfectly normal, but apart from a roof over our heads, and food on our plate, probably about the only thing we need as beings is LOVE.
So how can you tell the difference between a want and a need?
It can be difficult to dowse for something like this as your ego will get in the way. However, using the manifesting method of digging in ThetaHealing, you can get a good idea of what would happen if you had what you wanted.