For most people bodybuilding is a lonely endeavor. They are forced to lift weights by themselves, meaning that they lack someone in their corner and that can be bad on a number of levels. With someone to lift weights with, a person has someone to compete with thus keeping them motivated. They have someone who can spot them, ensuring that they will suffer minimal injuries during weight lifting. This also means that they have someone to celebrate with as well, a really nice feature when some goal has been reached. It is just a matter of finding the right person.
Finding that fellow lifter does not need to be a major problem. All you need to do is place an ad either at the gym itself or through some service. There are some groups that meet together with the sole purpose of finding gym partners, and various weight loss groups actually encourage pairing off for the sake of lifting weights. Some people actually find partners by inquiring at work You can even rope a friend or relative into exercising together. It really is not that hard to find that partner if you know where to look.
Just make sure that you and your partner have at least the same general goals or the partnership could actually prove disastrous for both of you. Just as it can power you and motivate you more powerfully to work towards your goal, a bad partnership can draw power from you. Nonetheless, a great partnership is something well worth attempting, especially if you feel something is missing from your workout and therefore worth checking out.