If you want some kind of tension, add a source of tension to the scene. Rolling dice doesn’t add tension by itself, so if a scene wouldn’t be tense without calling for a check, it isn’t tense. Fix that first, and the need for a check will arise organically.
LOL, try climbing 80 feet up a rope with
NO safety harness or line, etc. and tell me afterwards that it wasn't tense! I think you'll find it was
VERY tense, but I could be mistaken.

Many people like to climb IME because of the adrenaline rush they get out of it.
Add in any additional sources (weather, someone shooting at you) and I bet you would be in a very difficult spot.
Also, many people find tension in rolling dice (which is why people gamble with dice as well...) when there is risk involved, such as the danger from falling.
4 mile run without stopping is nothing to sneeze at!
Which brings up another interesting thing lacking in the rules. Nothing for any sort of distance run. The closest thing you have is the Fast Pace previously mentioned, which is fine for
walking, but not for any sort of run.
Example: an enemy force is attacking a stronghold. A PC manages to sneak out and break through enemy lines to run for reinforcements. If they can't make the run in time, help won't arrive quickly enough to save the defenders. The DM knows it is 10 miles, and the PC has two hours to get there.
Normally, 5 miles an hour is a very quick walk or slow jog. Even with breaks to rest IMO many people in decent shape (at all) could do this. But, sadly, the rules don't allow it. Fast pace is 4 miles an hour and the PC fails.
You have special movement rules for climbing, jumping, and even
crawling, but nothing for running. It isn't hard to come up with a rule for it, but still should have been included IMO.