Probably the easiest part of your muscle building routine would be picking out what routine you want to go with. After that, it's more than likely not so easy. Being able to set aside time for it, being able to find a way of enjoying it and wanting to continue, etc. It's just hard face it. Focus is probably the one thing that stands in the way of most people no matter what kind of exercise routine they are doing whether it's something simple or something as complicated as body building.
Get rid of the scales, that's right, hide that scale. It is way to hard to concentrate on your routine if you are focused on the scale. You need to understand that muscle is going to weigh more than fat so the scale is going to do you any good anyway, in fact if you've gained weight you may get discouraged, so get rid of it. Hide it in the closet but keep it from being easily accessible.
A good thing to do is to keep one of those cloth measuring tapes that you can use to occasionally measure your upper arms, thighs, calves, waist hips and chest. You can then keep track of all of your results in a workout journal. You should do this only about once every 2 to 3 weeks. Also, to pat yourself on the back, put a nice bright colorful sticker in your workout journal each time you complete your routine each day. Come on, even adults like a bright reminder they did good.
If you are working hard to also lose weight along with building muscle, have someone take a full body shot of you in your workout close and then put it on the refrigerator as a reminder and as an incentive for you to stay focused on your workout program. Then as you begin to lose weight and shape up take another picture and continue to do so whenever there are noticeable changes. This is a great way to keep you focused and encouraged.
Each day either before or after your workout take a look at yourself in the mirror and say something good about yourself, give yourself some affirmation that you are doing a good job and that you can do it, that you can continue to strive for your goal. It's always a good way to keep you motivated if you believe in yourself.
Don't do the workout alone. Sometimes it is simply much easier to keep focused on your goal if you have others working out with you. Each of you may have different final goals but you all have a goal and you all need encouragement. Working together you can encourage each other and help each other stay focused on what's important.