The Knock of Crieff is a great place to go for a wander if you don't feel like expending much energy or you want some fantastic views without too much exertion.
Paths are signposted to the Knock from Crieff town centre, but unless you feel like slogging up through the tarmac covered suburbs of the town, you'd be better to drive up to the Knock car park at the back of the Crieff Hydro.
From the car park, numerous paths lead onto the Knock and I would recommend taking one of the paths that lead you right round the side of this curious little hill before 
coming back over the tops.
If you just want a quick jaunt to the best viewpoint, take the path that heads straight up the hill, and you'll reach the top within half a mile. The views are fantastic all the way up and down Strathearn.