The "tired, aching or heavy" legs phenomenon is common that we all experience from time to time, particularly at the end of the day and in the summertime. In particularly, it is normal to have those legs feel like tree trunks after a rigorous exercise or a day at an amusement park. It is simply due to fatigue. However, if it is so much work lifting your legs to walk without prior physical exertion, they are not "normal" and deserve medical attention. It may indicate that your return blood flow from the legs to the heart is impaired. Weakened veins cause oxygen depletion in your legs, giving you that heavy sensation in your legs. People who have varicose veins
or other problems with venous insufficiency in the legs can lead to some leg swelling that gives a sensation of heaviness. It may also a serious symptom of peripheral vascular disease. A heavy leg sensation should be taken seriously as the problem can develop into complications so it is advisable to have intervened at the early aching or heavy stage. I would recommend that you schedule an appointment with a primary care doctor
to help you find the underlying cause of your condition and proceed to an appropriate treatment. Hope this helps. Good luck!