If the GPS tracking feature is disabled on your smartphone, you will be asked soon after starting the timr app if you want to activate the GPS tracking feature.
If you don't grant timr location service access, you can change this later in your smartphone settings.
1. Enable/Disable position tracking on your Windows Phone
To enable the GPS tracking on your smartphone go to your smartphone settings.
In the "Settings" you see the feature "Use GPS satellites".
Enable the feature by switching it to on.
2. Enable/Disable Position Tracking in the timr Windows Phone App
The timr Windows Phone App shows a cross-hairs icon on the top if GPS is active. More information about the Position Tracking in the timr Windows Phone App is available here.
You can also disable the GPS Tracking only for timr. Go in your timr App to "Settings". There you have the settings "Allow Localisation".
To disable the Position Tracking feature deactivate the small box on the left side of "Allow Localisation".