Magog, Eastern Townships of Quebec
The town is cosy and small, but is beginning to show signs of city influence, like the gourmet grocery store on one of the main thouroughfares, the plastic housing developments in the forest, and the fact that more and more people speak English. Despite the growth of the town, people are still friendly, the lake is beautiful, the air is clear, and there are plenty of outdoor activities to do in the summer and winter. It's also a prime spot for fall-foliage viewing.
Supposedly, you can swim in the lake but perhaps only if you have some Canadian blood. I preferred to fish and boat to small islands in the lake, and ride along the bike path (used to be a rail line, just like the P'tit train du Nord) along the lake and through the woods. The path doubles as a cross country ski trail in the winter. Mount Orford, surrounded by national park land, is a short drive away, as well as the popular Owl's Head ski area.