Just Google "Ontario rail trails" and save yourself the pretention and hype. And wearing gawdy, silly canary outfits too. Hardly anyone is using the trails and many close to the GTHA are accessible by GO both ends, so you can take a GO train or bus out to one end of the trail (some cycling is needed in most cases each end) and back on another GO route the other end. The Caledon Trailway is an excellent one for novices, as is the Cambridge to Brantford leg of the Cambridge to Hamilton (or Port Dover) one. 

Hamilton has a number of easily accessible tail trails. You don't need to go to Niagara and be a tourist-consumer. Elora to Cataract is a superb rail-trail.

There's quite a few more, just Google. Here's an example:
http://ontariobiketrails.com/rail-trails/