One of Mark Sisson's Laws in his excellent Primal Blueprint - which I really need to review properly is Primal Blueprint Law #3: Move Frequently at a Slow Pace
I did that yesterday in the Grey Corries, some mountains in the Highlands just along form Ben Nevis. The guidebook said 21km and about 1200m of ascent but it felt a lot more! 9 and a half hours but we did not rush it, lingering on the ridge and soaking up the exquisite views.
Here are some photos:
There is a full write up here.