Apple Watch Series 3 - Outdoor Run

Hi!

I have a Apple Watch series 3. Recently when I go out for a run with my friends, I noticed that my km is always short than that of my friends. My running pace also seem to be faster than the others, and when I upload my run to the strava app, it seems that my distance I ran was correct in the first place. It seems that my Apple Watch distance measure lags when I am busy with the outdoor run activity.

What should I do if I want my watch to measure the distance accurately again?

Please help!