Yes, if you'd like to train the Physical aspect of a driver, you can change it from 4 available options: All, Driving Ability, Mental, and Physical. (Training "all" trains the lowest attribute of the driver)
If you're on the app, here's what you do:
Tap this silver button.
You'll notice the driver health and progress bars disappear and see this:
Cycle through the available options and begin training. :)
For PC, you will see the options like this:
That will be the only step for PC and you can begin training.
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