An underactive thyroid, also known as hypothyroidism, is a condition in which the thyroid gland fails to produce necessary levels of hormones needed by the body to function properly. In the long term, hypothyroidism can cause obesity, joint pain, infertility and heart disease. Some women may need medication to control their thyroid problem; others may find certain lifestyle changes and natural supplements to be helpful. Make sure to consult your doctor for a proper diagnosis before trying self-care methods.

Get regular cardiovascular exercise of any kind for at least 30 minutes a day every day, or as often as possible. Cardiovascular exercise increases metabolism and boosts levels of serotonin in the brain that can be lowered in individuals with hypothyroidism. It also stimulates the circulatory system.

Eat a healthy, whole-food diet, including fresh fruit and vegetables, whole grains, lean meats and fish. Eliminate all processed, refined foods and foods high in fat, sugar and salt.

Boost your intake of thyroid-friendly foods and eliminate other healthy, but unfriendly foods from your diet. The University if Maryland Medical Center suggests boosting your intake of foods rich in B-vitamins and iron, such as whole grains, fresh vegetables and sea vegetables 1. It also recommends avoiding certain foods that can affect healthy thyroid function, including kale, spinach, broccoli, peanuts, linseed, cassava, brussels sprouts, cauliflower, turnips, soybeans and millet.

Supplement your diet with omega 3 fatty acids -- fish oil -- and L-tyrosine. The University of Maryland Medical Center suggests taking 1 to 2 capsules or 1 to 2 tbsp 1. of fish oil daily and 500 mg of L-tyrosine daily. Consult your doctor before taking these supplements.

Practice yoga, focusing on poses that stimulate the thyroid gland 2. According to "Yoga Journal," six yoga poses encourage healthy thyroid function and should be practiced regularly 2. These include bridge pose, full boat pose, plow pose, king pigeon pose, shoulder stand and upward-facing two-foot staff pose. If you are new to yoga, find an experienced professional who can introduce you to the basics of yoga and help guide you through a practice that will help stimulate your thyroid 2.