I'm not sure I do, but living in a hilly corner of our wee island, I'm trying to face them. For the past three weeks I'm been mastering the easy 30m in 1.2 km incline back to my house.
I thought I'd push myself a bit more and try another hill; a long, gradual climb (and one I love to whiz down on my bike!), Today was my tempo run using the 5K+ Stamina podcast and I thought the hill would add a wee bit extra. Well it was tough - tougher than I thought it would be to run up. But run it I did. All 123 metres or 400 feet uphill in 2.4 km (1.5 miles). I felt like stopping several times, but didn't - although it was difficult to keep jogging on the spot when the postie passed me several times (he passed me, then I 'passed' him when he went up a farm track - twice).
I kept to the 160 bpm pretty much by greatly shortening my stride going up, although my breathing was terrible. I must practise deep breathing again. It was wonderful when I turned around to return. I felt I was flying down that road!
I'm not sure about my split times as Runkeeper on the iphone went potty again today. (I'm desperate to get to town to collect my new Garmin that the shop ordered in for me and which has arrived, but don't have transport at the moment), My overall time was 7.5km in 50 minutes.
ps, This is not even the top of the hill. The track continues another 2km up into the forest gaining another 150m in height.