Suggest Remedy For Sore And Painful Legs

I go on daily walks (up to 2 miles) and have never had a problem with my legs before but lately I've noticed that after going just a few blocks the front of my lower legs will start hurting accompanied by a burning sensation. The pain usually goes away soon after resting unless I have to push myself (like when I walked too far and need to get back home), in which case the front of my legs tend to stay sore for a day or so afterwards. What could be causing this and what can I do about it?