The Caledon Hills, Dufferin Hi-Land and Blue Mountains sections of the Bruce Trail are quite hilly, with lots of steep ravines. The cumulative elevation changes are quite apparent and if you hike these areas a day or two after training your legs with heavy weights at the gym, you will hurt.
Here are a few photos from my 40-kilometer (25-mile) Shelburne hike (Map 20 of the Bruce Trail Reference: Edition 25), starting at the Boyne Valley Provincial Park and stretching to a turn-around point a few kilometers north of Kilgorie. In one of the photos you can see the giant windmills Ontario built as a source of green power: you have to look closely at the horizon. The photo was taken from the top of Murphy’s Pinnacle. Here is the link to a large scrollable version: Windmills.