Cancer is a common disease and is growing in incidence and prevalence. It is expected to become the number one killer of humans in the coming decade. It is associated with considerable suffering, decreased survival, and huge economic costs. Death is usually due to metastasis. Major cancers include those of the lung, breast, colorectum, prostate, stomach, and liver. It results from a complex interaction involving genetic, environmental, and lifestyle factors. It is estimated that up to 95% of cancer events are attributable to lifestyle factors such as physical inactivity, cigarette smoking, poor diet, alcohol, and obesity. Smoking cigarettes is a major cause and may be responsible for 40% of all cancer cases in the US. Obesity is the next major modifiable lifestyle factor. The impact of improper diet and alcohol intake is estimated at being more than 5% followed by lack of physical activity. These factors are modifiable and can greatly help reduce the risk of common cancers, improve their management, and beneficially affect their prognosis. In addition, following healthy lifestyles will help mitigate the deleterious effects of many co-morbid chronic diseases that cancer patients have. This manuscript discusses the impact of these major lifestyles on cancer.