Focus on doing a lower intensity...lower heart rate period of time on hills.
For example I might do 80 minutes at a 3 speed 25% incline keeping my heart rate around 140.
This trains you for endurance. I think it also serves as a foundation of strength to avoid injury. It is the method bodybuilders use to shred that last bit of fat to show their pretty muscles!
If I am short on time I might just kick up the intensity.
If you have no access to a steep treadmill...find a hill to climb!
This is my evening workout...but do it when you please!