As most anyone can tell you, exercise has many health benefits, including improved sleep patterns, improved mood and relaxation, better energy and a revved-up metabolism. Exercise can also help your body "detox" through sweating (when sweat is washed off promptly so as not to be reabsorbed.) Deep breathing promoted by exercise also helps the detox process via the lungs, and it helps increase alkalinity through better oxygen uptake. And while not a specific requirement for either weight loss or weight management, exercise makes both far easier to accomplish.
Anyone starting out on a new exercise program after years of inactivity should really start very slowly, and protect overall long term health by also improving diet and adding in appropriate supplements. The key in both strenuous and beginning exercise programs is to maintain and improve fitness over the long term, rather than put yourself in a situation in which you become continually side-tracked by injury and exhaustion - or worse - from exercise that is unsuited to your needs and present condition. Remember, exercise should give you energy and improved health, not rob you of it.
The level at which to begin a new exercise routine, therefore, is to start at YOUR level - even if it means other people would laugh at your plan. If this means a 10 or 15 minute routine of deep breathing and stretching, so be it. Add in a few minutes of meditation or quiet time, preferrably in the sun, to nourish the soul and you are off to a really good start.
If you have a physically demanding occupation - such as parenting small children, then this activity needs to be considered part of your program. A few minutes of stretching and deep breathing can be invaluable aids for dealing with the stress that comes with parenting - or most jobs. Add in a two or three 20 minute walks per week with the kids and build as you are ready.
Regarding the intensity of exercise required to lose weight, here is what one recent study which was presented at a meeting of the American College of Sports Medicine found regarding the benefits of low stress exercise as an aid to weight loss:
A team of researchers from the University of Colorado recruited 40 subjects. Half were obese and half were normal weight. Subjects were evenly divided by gender as well. Fat mass and bone mineral content were measured before and after the test. Carbon dioxide production and oxygen consumption were also measured during treadmill tests that compared the amounts of calories burned while walking at different paces.
The results: While walking a mile at a leisurely pace subjects actually burned more calories than walking at a faster but normal pace. And this was uniform among all subjects.(From Health Sciences Institute E-letter)
Too much exercise - or perhaps more accurately over-exercise for your level of fitness and conditioning - can be as bad as too little. Those who engage in more demanding exercise need to make adjustments in both diet and supplements to compensate for the higher acidity created by heavy exercise not to mention the nutrients lost through heavy exertion. Consider that extra nutrients are required to reap the true benefits that exercise is supposed to bring.
Just as important for any exercise program is to get adequate animal protein and fats to help rebuild muscle, bone and connective tissue together with adequate amounts of alkaline producing "most favorable" carbs.
It may be good to repeat here what Diane Schwarzbein, M.D. says about low-fat diets and exercise in her book :
You can see initial good results with a low-fat diet. When you exercise and eat a low-fat, high carbohydrate diet, excess carbohydrates will be turned into cholesterol and fats that are then used by the body as energy. During this stage, your cholesterol profile will significantly improve. But a low-fat, high carbohydrate diet burns muscle mass, especially if you are exercising. This causes your metabolism to slow down, which in turn lowers your requirement for energy. Now any excess carbohydrates you eat will be converted into cholesterol and not used. Over time, your cholesterol will rise. pp 90-91
Likewise, Severe calorie restriction is never a good idea and may eventually bring more problems than it solves, most especially when engaged in a strenuous exercise program. Particularly for the older set (over 35 or 40), proper supplementation can play a key role in maintaining health as it helps to avoid injury and exhaustion - or worse. This is key, since - as Richard Passwater and others tell us - trace nutrient deficiency WILL eventually cause "health bankruptcy". How soon depends on environment, genetics, diet and most importantly - lifestyle (sometimes even those lifestyle changes involving a new exercise program.)