Ride on a flat course or spin bike. Focus on keeping your pedal stroke smooth and learning to be 'light' on the pedals. Put as much pressure pushing down on the pedal as you do on pulling up the opposite pedal. RPE should be light - 5/6 out of 10. Go right into the run brick!
Run on a flat path, track or treadmill. You can use the 8/2 method of 8 minutes running, 2 minutes walking. While running, run like a Kenyan - smooth and efficient. RPE should be light - 5/6 out of 10.