Or see who can lift the most weight for 4-5 reps. Just make sure the contest rules specify doing the exercise right, since sacrificing form to lift more weight can be dangerous. Work with a trainer or coach. When there's someone watching you and keeping an eye on your progress, there's incentive to keep going. Force yourself to hang in there religiously for the first three months.
Nothing sustains motivation better than results.
However, whether you're a beginner or a competitive bodybuilder, your muscles must be given enough time to adapt to the growth and recovery periods that strength training requires. Though you may see some results, like increases in strength, early on, noticeable changes in your physique CAN take up to three months. It also takes that long to establish a rhythm and discipline to your training schedule, but after three months of dedication, you'll be a lot less likely to fall off the training wagon. As soon as you miss a workout, re-motivate yourself. This is the danger zone, the time when most people start giving up.