Does your Google Fit GPS tracks look like mad? There is a very simple solution for this issue. When it works in the background, the GPS signal is collected rarely. However when you use navigation, the GPS signal is updated frequently.
To overcome the problem, simply launch navigation to some distant point and make it silent to not annoy you. Unfortunately, it requires your manual intervention, but that's better than nothing. I recommend to stand up from your desk, leave the laptop and go training! Have a great day!