The gym is an extraordinary tool, and a place we have a love and hate relationship with. It has the power to recreate ourselves, reduce stress, improve physique, and make you generally more vibrant. The one downside is we must find time to go to the gym and we must go, otherwise failure is inevitable.
When you first start working out you will need a plan, and you will need to consistently follow it if you want results. Working out is an art and science, you must plan it carefully and it will in return sculpt your body and improve you as a whole. To begin, you will need to work on your cardio, because chances are you have been doing minimal activity for a long time and as a result you need to strengthen your heart before intense exercise.
As a result, for the first couple of weeks you should focus on just running; slowly every day try to run for longer and faster. It will be difficult at first, but it will become easier and easier over time. This will build up a base for you and eventually you can transition to full body workouts. When you run you are essentially strengthening your heart. As it gets stronger you will be less tired and able to perform more difficult exercises, which will lead into using weights.
When transitioning to weights you will want to plan out which body parts you will target throughout the week. A good start would be to separate the parts as follows chest, legs, shoulders, back, arms, then take the rest of the week off. This order and arrangement can be changed of course, but this is an excellent way to start. Each day you do a different body part as listed, then take a couple of days off and begin again.
Next, you will want to do 4 exercises per body part. Begin with compound lifts and move to isolation exercises. Compound lifts are exercises that focus on more than one muscle at a time such as bench press, dead lift, squats, pull-ups, pushups, etc. Then proceed with isolation, which could be bicep curls, lateral raises, leg extensions, etc.
Once you have designed a plan based on these criteria you need to decide how many sets and reps of each exercise you will do. Typically you want to do 3 to 4 sets per exercise; this means you do the exercise, then take a break 3 or 4 times. Now the question that remains is how many reps? Each rep is performance the full motion of the exercise, typically you want to do anywhere from 6 to 12 reps.
Determining which rep range to use depends on your goals. 6 to 8 reps, tends to build muscle, but of course you must lift heavy enough where 6 to 8 reps is difficult. 10 to 12 tends to do hypertrophy and/or endurance. Generally, your muscles get bigger and you build up a little bit of strength, but you're doing more, so you can last longer.