When you're in your 20s and 30s, the right lifestyle and screening tests can go a long way to keeping you healthy.

1. Start a Heart-Healthy Diet-and-Exercise Plan

Skip the fried and fatty foods, and try to get at least half an hour of exercise every day. Eating right and keeping active are the gifts that keep on giving.

If you set up these habits now, the benefits will last a lifetime. And if you plan on having children someday, it's a good idea to take a multivitamin that gives you plenty of folic acid -- between 400 and 800 micrograms a day. Start taking folic acid at least 1 month before you plan to get pregnant, and keep it up during your first trimester.

2. Work on Your Relationship With Your Doctor

Find one you trust. Before your appointment, make up a list questions, such as: What contraceptive method is right for me? What's the best way to prevent STDs? What vaccines do I need?

3. Know Your Family Health History

Did your sister, mother, or grandmother have breast cancer or heart disease before they turned 50? Does diabetes run in the family? These are important questions to ask your family to help your doctor figure out your own health risks.

4. Don't Forget Key Screening Tests

Make sure you get a Pap test to check for cervical cancer every 3 years starting at age 21. If you're 30 to 65, you can keep getting a Pap test every 3 years, or you can get it along with an HPV test every 5 years. That other test is useful because most cervical cancers are caused by an infection with HPV (human papillomavirus).

If you're sexually active and have a higher risk for STDs, get tests for chlamydia and gonorrhea every year. Take an HIV test at least once, more often if you're at risk. Also consider tests for other STDs like trichomoniasis, syphilis, and hepatitis B.

Check your blood pressure every 2 years if it's normal (lower than 120/80). If it's high, or you're at risk for high blood pressure, you'll need more frequent checks and diabetes screening tests. Also, get your cholesterol tested, and ask your doctor how often that needs to be done.