If you like walking, check out the Thames Valley Trails website: http://www.tvta.ca/
Also, discover Westminster Ponds. There are several entrances to the ponds, but the easiest one is probably the one off the Tourism London Information Centre at 696 Wellington Road. Website: http://www.ontariotrails.on.ca/trails/view/westminister-ponds---pond-mills-conservation-area
Essentials: bottled water, bug spray, camera, cellphone (in case you get lost)!