If you are interested in starting to build your bodies over all strength it is a good idea to setup a simply workout routine. If you only have 3 days a week to put towards your strength training, that will be plenty of time to get in the work you need to do to see a difference in a short period of time. The big thing about strength training is that you can give consistent effort and you take time to focus on separate parts of the body each day that you put forth effort in your workouts.
Day 1 should consist of a workout for your arms and upper body. You may find that working on push-ups, lifting on the bench press and pull-ups are a good set to take on for upper body strength. There are other exercised that some like to focus on like curls or using the preachers bench at the gym to build up your biceps. Either way, you will only want to focus on your arms, shoulders and you lats. These muscles are going to make up the first muscle group.
Day 2 can consist of working out your stomach and your back. These 2 muscle groups are done together because they are considered to be “reflex muscles” simply meaning that any time you are working one, you are also working the other. When one muscle is pushing the other is pulling, so you generally are working your stomach and back muscles together. Sit-ups, twists and crunches can all be good examples of abdominal exercises. Depending on what gym you are working out at, there are usually some machines that are built to help you focus specifically on your back muscles too.
Day 3 you will want to focus on your leg muscles. The quads, hamstrings and calves will all be worked out in this set of your work out routine. Leg presses, squats, dumbbell lunges are all good exercises to work your leg muscles. As with all other exercises you want to do all motions slowly and under controlled environments to avoid pulling muscles or other injury.
You do not want to do other aerobic exercises like running while strength training; this can be seen as anti-productive. You may want to fit this type of exercise in on other days of the week. If you separate each day of your workout with one day of down time, this will give your body significant time to rest and repair muscle between your workouts.