When I travel out of station my exercise ring doesn't move

Well the whole day I was in a different city, though I didn't record any workout I was continuously moving during the day. The exercise ring didn't move and at the end of the day it showed 0 out of 30 mins of exercise. Earlier it used to track my walks and physical activity during the day. Now it has just stopped. Not sure what's the problem. Please help. I am on Apple Watch Series 4(GPS+Cellular), Watch OS 6.1