If you're starting a self guided fitness program you should complete a pre-participation assessment, like the PAR-Q, in order to identify if you have an increased risk and to determine if a medical evaluation is warranted.

If the answers to PAR-Q suggests it's OK to exercise then it would be a good idea to have a fitness evaluation.

From the ACSM's Guidelines for Exercise Testing and Prescription (2006-seventh edition).

Physical Activity Readiness Questionnaire (PAR-Q)
Please answer each question honestly, use common sense as your guide.

1. Has your doctor ever said that you have a heart condition and that you should only do physical activity recommended by a doctor.
2. Do you feel pain in your chest when you do physical activity?
3. In the past month, have you had chest pain when you were not doing physical activity?
4. Do you lose your balance because of dizziness or do you ever lose consciousness.
5. Do you have bone or joint problem (for example, back, knee or hip) that could be made worse by a change in your physical activity?
6. Is your doctor currently prescribing drugs (for example, water pills) for your blood pressure or heart condition
7. Do you know of any other reason why you should not do physical activity?

If you answered YES to one of the questions talk with your doctor by phone or in person BEFORE you start becoming much more physically active or BEFORE you have a fitness appraisal. Tell your doctor about the PAR-Q and which questions you answered YES.
You may be able to do any activity you want as long as you start slowly and build up gradually. Or, you may need to restrict your activities to those which are safe for you. Talk with your doctor about the kinds of activities you wish to participate in and follow his/her advice. Find out which community programs are safe and helpful for you.

If you answered NO honestly to all PAR-Q questions, you can be reasonably sure that you can start becoming much more physically active-begin slowly and build up gradually. This is the safest and easiest way to go. You should take part in a fitness appraisal - this is an excellent way to determine your basic fitness so that you can plan the best way for you to live actively. It is also highly recommended that you have your blood pressure evaluated. If your reading is over 140/90, talk with your doctor before you start becoming much more physically active. PAR-Q developed by The Canadian Society for Exercise Physiology.

After completing the PAR-Q and if your want more information concerning your health status go to the coronary artery disease risk factors and major signs or symptoms of disease.