First, please check your spam and promotion/update folders. If you still cannot find your email summaries, follow the steps below. You do not need to follow these in chronological order. If one of them solves the issue for you, you do not need to perform the others.
Log out and back in again
1. Open the app on your Apple Watch
2. Scroll down and select 'Settings'
3. Click 'Log Out' at the bottom of the page
4. Force close the app
(long-press the side button until you see 'power off' then long-press the crown button until the app dismisses from the background)
5. Re-open the app and Sign In again
Resend the last workout summary email
1. Open the app on your Apple Watch
2. Scroll down and select 'Settings'
3. Find 'Email' and click 'Send Last'
Change your email address manually
1. Open the app on your Apple Watch
2. Scroll down and select 'Settings'
3. Find 'Email' and click 'Email Settings'
4. Manually enter the email address you wish to receive summaries with. (Turn off 'Hidden Email' if it's turned on)