The nature of the mitzva
There is the positive mitzva to love your fellow Jew like yourself. This is a mitzva that can be done whenever we meet other Jews that can be many times a day! Some even have the custom to mention accepting upon themself this mitzva in the morning before shachris after entering shul.
There is the famous dictum that R’ Akiva said about this mitzva – it is a rule for the whole Torah. This is borne out by the story of the convert who came to Hillel that he was willing to become Jewish only if he could learn the whole Torah on one foot – he was told this mitzva only in different words: What is hated to you do not do to your friend. The rest of the Torah is additions on to this.
What is included in the category of “your friend”? Someone who follows the laws of the Torah.
The reasons behind the mitzva
Every person naturally feels animosity to another since each person wants everything for himself and the presence of another limits this. The way to resolve this is to realise that the other person is really connected to you and is coming to assist and not oppose. By loving the other, people can do many more things, as two people are better than one and this creates a situation of harmony.
How to live with this mitzva
Shortly after waking up, even before coming in contact with anyone else, one should accept upon himself this mitzva of love your fellow Jew like yourself. Some people do it at the beginning of davening. When coming in contact with people one should try to positively apply this mitzva and put it into practice looking for something good about the person that he can latch onto to love him.