Fitness comes in all types and different forms such as Powerlifting, Bodybuilding and crossfit.
Powerlifting is a sport that requires many hours of training in the gym. Powerlifters train different than bodybuilders by using lower reps. Bodybuilders normally train with higher reps and they rely on volume to build larger muscle bellies. Powerlifters spend most of their time in the gym with one rep max or PR. These lifters normally focus on lifts such as Bench press, Deadlift and squats. There diets are normally more relaxed than bodybuilders. Ther pretty much eat anything they say, and take fitness supplements such as creatine and prohormones like M-sten and epistane. Products like epi and msten should be used with caution these products can cause serious liver issue if not used properly.
Another form is bodybuilding, these athletes use high reps and eat high protein diets. These type of lifters focus on staying lean and building big round muscle bellies. They also use a ton of different fitness supplements such as Amino Acids, creatine, Fat burners and Epi-Andro for cutting. Bodybuilders normally train year around and can spend up to 16 weeks dieting for a show. A big player in the bodybuilding supplement game is Blackstone Labs, the leader in hardcore bodybuilding supplements. Another great starter pre-workout supplement is Krush It.
If you are looking for extreme exercise we suggest looking at cross fit. This is a more extreme type of cardio exercises, crossfit uses weightlifting and cardio exercise to get people in shape. Most crossfit athletes use a paleo style diet. This diet has also been known as a caveman diet since you only eat foods that cavemen would of ate. As far as fitness supplements goes they can use several different types. BCAAs work good to help give athletes a little more gas during training. FIsh oil is another staple in most crossfit athletes supplement plans. Some athletes use something to support the joints as well.
All three of these types of fitness will help you get in shape and build muscle. Pick the one that fits you best and give it a try. Best of luck on your new adventure. Another great muscle builder is Tresta if you are looking to use a prohormone.