Still sore after 30 days

BigVeggieDream

I walk 6 days a week, alternating longer/shorter distances. Not surprisingly in the beginning, I was sore and my muscles tightened up within a half hour of completing my walk. It's been 30 days and this is still happening. I would have expected this to go away or at least minimize. I stretch before the exercise and warm up. The rest of the day, I stretch a few times more because my muscles tighten up. What's going on here?