You can make changes to an ongoing ride without starting a new Activity.
Changing Profile mid-ride
You can change the selected profile by going to the Home Screen and selecting a different profile. The ride does not need to be paused to do this.
Just long-press the bottom right (E) button to go to the Home Screen.
Add/remove/change Route mid-ride
You can add, remove, or change the route without pausing a ride.
You will see this option under the Quick Action Menu
Add/remove/change Workout mid-ride:
You can add, remove, or change a workout after pausing a ride.
You will see the option on the Workout Screen.
To add a workout mid-ride you must have a workout page in your selected profile.