Connect Garmin Connect

Garmin will ask which data to share. To include your training from before today, switch on Historical Data Export.

Garmin's permission screen with the Historical Data Export toggle being switched on
The toggle is off by default. It's the one that unlocks your history.
Continue to Garmin

Missed it? Reconnecting Garmin brings the same screen back.

Manage this and other settings anytime in your account at app.sweatstack.no