The contest mentality is definitely a different one. Why would anyone want to have a restricted diet, long cardio sessions and intense weight training sessions? What benefit is there to the person competing? Let me try to answer those questions for you in the following paragraphs.
Honestly, the dieting part of contest preparation didn't bother me in the least. What I do is set up a simple menu and stick to it. I keep the variety at a minimum because I have worked to dial in the macronutrient ratios. I find it simpler to just stick with less variety in order to achieve the results I am after. To me it doesn't matter if I eat the same food every single day. Food is simply fuel and nothing more.
The Long Cardio Sessions
Cardio is boring. I will not argue that point. However, when you attack it with the proper mindset it isn't so bad. You have to tell yourself that it is a necessary evil and then, like Nike says, just do it! I find that mixing up what you use for cardio works wonders. I know most bodybuilders swear by the step mill and stick to that exclusively during contest preparation, but I believe that any intense cardio will do the trick. I stick to the step mill very closely, but not exclusively. I incorporate the treadmill on a regular basis, using various types of treadmill workouts I have designed myself. I also incorporate outside cardio. I will routinely run on a track or do long, brisk walks. Whatever it takes to raise my heart rate. I also use a heart rate monitor to get good results.
Intense Weight Training Sessions
This part is the easy part for me. I love intensity when training with weights. I love pushing hard and getting great gains as a result. I have used High Intensity Training with great results. I have used body part splits with great results as well. It is all about the intensity.