First things first, please whatever you do --- DO NOT STAVE YOURSELF! The key to keep and forming a healthier lifestyle is making small changes after small change. And I definitely think that you have the right idea there :P I personally do not believe diets work but there are certain things that you should stay away from: Junk food & Junk drinks. Anything with high sugar is initially going to release chemicals into your brain that will give a very pleasurable feeling. However your body is actually forced to release other chemicals to counter the simple sugars in your bloodstream. After the chemical reaction is complete, your body becomes even more tired and crashes. There were a series of studies I read about stating that when you desire sweets, your body actually needs to consume fruit, which are complex sugars. They break down slower and raise sugar level in your blood stream slower. However when you eat fruit, drink water. Being dehydrated, even slightly, can cause fatigue. 2) Slowly begin to cut back on the amount of calories you consume, and try to eat balanced meals: a servering of Meat, Veggies, and a Carbs. By slowly cutting back, you help your body adjust and the more gradual the process more likely the changes you make will become a lifestyle change. Lifestyle changes is our goal. Please eat carbs, but make sure they are whole grain! Carbs have gotten a very bad name recently but honestly if you want to begin training your body needs energy. Carbs, are not as simple as the sugar in junk food, they give your body the quick energy. Meanwhile protein found in meat is important for supplying your body with the nutrients it needs to build and repair your body from workout. Protein, since it is a more complex organic compound than carbs, breaks down slower and will keep you fuller for longer. The vitamins found in veggies in general help your body to absorb the nutrients from foods meanwhile supplying your body other nutrients it needs. Diet is honestly where you will see the biggest results! 3) Since your physical fitness level is if of concern you should invest in a watch that can keep track of your heart rate. Your goal is to work out at your target heart rate.
By working out at your target heart rate, you can ensure a safe but also effective work-out. Please use the link to the American Heart Assoc. to find your Target heart rate zone.
4) The trick to making exercise something that your will stick with is keeping it fun. People that fall into routines get bored, hit plateau and ultimately quit. Even is this mean you have to be a chain-video-workout-junkie it does not matter. I personally am still enjoy Tea-bo from Billy Blank, even though now it is very dated. My other trick to finding new moves that i can easily do in my living room is i look at fitness magazines and pick out moves that I feel comfortable with. These are national magazines, with fun little spins on an old thing.
5) Please don't get discouraged! Keep in mind that it takes three weeks for your muscles to adjust to working out and it actually takes six weeks for your body to begin to build new muscles. Don't be scared of becoming big from weights. Cardiovascular workouts while you are preforming them burn more calories then weightlifting however the muscles that can be developed from weightlifting will continue to burn energy through out the entire day. If you do not want to build big muscles do many repetitions with lighter weights. I usually test my max weight and then lower that amount by three or four standard deviations. Two pound weights can become very heavy after doing 90 repetitions broken up into 3 sets.
6) IF you have the chance to go to a gym, please talk to the personal there. They are there to help you and more often then not are bored out of their skulls. These are generally people that love to work out and many love to share what they know. IF you feel that your uncomfortable doing an exercise alone, ask someone to spot you or even help you with technique. Plus it is a great chance to meet new people and spar with your wit against theirs. If you do choose a gym and since you have three kids, try to find one that has a children's program or even make your kids a part of your workout. Make them blow the whistle, count, or cheerlead. Let them know why Mommie is working-out.
Hope this helps.