Now Rustan has started to demand really long walks in the evenings: The ordinary walk of 45 min or so is no longer enough. Today I spent more than one hour with him, walking more than 3 km, and when we returned home (to bring out one of the others), he went to the door and demanded to go for a walk!
He doesn't take it very easy when we're out; He runs at a fair clip almost most of the time.

I suppose it's that the light and temperature is just right for them this time of year. Dark enough to go most places they don't when there's daylight, cool enough that an hour places no great demand on them.