How can we understand this commandment and why is it difficult. The Ramban states that it isn't enough that if we see our fellow poor that we should want him to be wealthy. Or if we see that he is ignorant we should want him to be smart. But just as we want for ourselves every good trait and quality we should want the same for our fellow. We want to be wealthy, smart, good-looking, intelligent, honored, loved, funny etc. we should also want these same attributes for our fellow. Why is this not always so easy? I think the real reason we don't always want all the good for our fellow, is because we somehow feel that if our fellow has success then this will take away from us in some way. We think if he is wealthy then he is some how taking money from me or if he is smart then it takes away from me. But this way of thinking is really due to our lack of belief and trust in G-d. G-d is infinite and His ability to give is infinite. What your friend has in no way will ever detract from what you have or can have. With this in our mind and hearts it will hopefully be a little easier to fulfill this commandment of loving our fellow.