Bodybuilding for the Beginner or Advance is the same thing "Lifting Weights to change your appearance."
However, for the "Competitive Bodybuilder, the one muscle that needs the most changing is the Mind.
When working out, we think of how the muscle feels and imagine what it will look like weeks and moths down the road. To get there, we challenge ourselves, our discipline, our drive and will to push beyond our expectations to rival the bet of what we've seen.

Visually, competitive Bodybuilders must imagine what the end results will look like, then take the necessary steps to achieve that desired look.

Most important change after Mind Set is Nutrition.

The Competitive Bodybuilder has to radically alter the food choices that will help Build the muscles and not simply eat for satisfaction and flavor. This is where the rubber meets the road or we separate the Men from the Boys. Weeks and months on endless diets to achieve the lean muscular look requires sacrifice and will. The power to say, "NO" to your favorite foods time and again as well as having to be able to eat 6 and 7 times a day. There is nothing "Normal" once you've committed to become a Bodybuilder. From Sleep, train, rest and recover everything requires more!
The beginners mind set is;
 "I can't do this or I dont wanna do that." Placing limitations on what one can achieve is a common stumbling block for beginners simply because they are not will to take their bodies where their minds cannot see.
There is plenty of pain involved when you get to competition stage. Muscles ache, their sore and tender to the touch. Many times a beginner may move towards competition only to find out that the road is full if twists and turns and having a "Normal" schedule is more suitable than beating yourself up physically and challenging yourself daily. Hence, there are very few Professional Bodybuilder and many weight lifters.

Bulking for size requires an athlete to eat more than what is considered normal i.e.; 3 Hot meals and a couple snacks a day. A Bodybuilder who competes is also competing at the dinner table. The athlete who trains 2 or 3 hrs a day for a contest for 14 weeks at a time consumes approximately 5 to 6 meals a day while taking in about 2 gallons of water! This is a radical departure from wanting to look good! These guys and girls want to look great and the human body thrives off of regular food consumption. Energy foods like carbohydrates: Potato's, Rice, Pasta, Fruits and muscle building foods like these Proteins: beef, Chicken, Fish, Turkey and Eggs. All the while getting plenty of helpings of leafy greens: Salads, Broccoli, Asparagus, Green Beans, Etc.

Eating every 3 hrs is routine for the completive Bodybuilder and large grocery bills are but a few inconveniences but the reward is worth the wait for many as illustrated by the number of participants in the sport world wide!
Typically, after the Bulking phase of packing on the Beef, a bodybuilder will spend 12 to 14 weeks trimming down the excess body fat through low carbohydrate consumption and protein loading to build and preserve the hard earned muscle. A shedding of 20 to 25lbs for competition is not unheard of and pretty typical of top bodybuilders. The beginner has trouble making it past the first 10lbs and first  weeks. Challenged by the fear of failure and the element of surprise. The work gets extremely hard and the results come even harder after the first 6 weeks. Beginners seem to have a negative mind set pertaining to how hard things are and how bad they feel while the competitive bodybuilder relishes the challenges and welcomes the pain and works through it.

The strength of many athletes is found in the "Mind Set."

Winners dont relate to pain and quitting, they are necessary for them to push beyond the mental barriers and limitations that Doubt can bring.

Competition is a yard stick to measure what we can do and how far we can go. While Drugs are prevalent in many sports including Bodybuilding, it is the individual athlete that is left to make career and life changing decisions about how far they want to go with their development and at what risk.

The best laid plans can go astray when you lose sight of where you want to go with your body and what you want it to look like if you dont monitor it closely. The worse thing that can happen is someone tells you can do it or your no good and you wake up 5 years after your Professional career is over like mine and your on the verge of entering the Bodybuilding Hall of Fame in 2007!

I have heard of stranger things happening but I never saw that one coming nor being on the Promotional end giving others the opportunity I had as a Teenager to follow their dreams wherever they may lead them.
Strength & Honor!
Shawn