A regular healthy life style with good diet, exercise and adequate sleep can help you a lot. A daily walk or following a simple exercise routine a few times a week will help your immune system not only fight off simple bacterial and viral infections, but may actually decrease the incidence of illnesses such as heart disease, osteoporosis, and cancer.
Physical activity may help by flushing bacteria out from the lungs (thus decreasing the chance of a cold, flu, or other airborne illness) and may flush out carcinogens (cancer-causing agents) by increasing waste output, such as urine and sweat. Exercise is responsible for sending antibodies and white blood cells (the bodys defence cells) through the body at a quicker rate. As these antibodies or white blood cells circulate more rapidly, they could detect illnesses earlier than they might normally. The increased rate of circulating blood may also trigger the release of hormones that warn immune cells of intruding bacteria or viruses. Furthermore, the temporary elevation of body temperature may inhibit bacterial growth, allowing the body to fight the infection more effectively. (This is similar to what happens when the body has a fever.) Finally, exercise slows down the release of stress-related hormones. Stress increases the chance of illness, so physical activity could reverse this factor.
Diet has an important, though perhaps an indirect role and excesses or imbalances in the diet can have negative impacts on health, resulting in disease states. In general, eating a variety of fresh, whole (unprocessed) foods is better compared to eating a diet based on processed foods. In particular, fresh, whole foods provide higher amounts and a more favourable balance of essential and vital nutrients per unit of energy, resulting in better management of cell growth, maintenance, and cell division as well as of appetite and energy balance. A generally more regular eating pattern (e.g. eating medium-sized meals every 3 to 4 hours) has also proven more metabolically favourable than infrequent, haphazard food intake.