Don't spend your days inside. Spend as much time outside as possible to get used to the conditions. I can't vouch for Canadian weather but here in the US we see heat casualties because kids went from the TV to Basic and the heat killed them. I'll let my Canadian brothers elaborate more on this.
Once again, FF has come up with outstanding advice.
I'll add to the climate changes and training in extreme weather conditions. Up here in Canada, for some reason where ever there is a Base it is put where the most extremes that mother nature can put forth happen. You will be out there doing something as simple as a run in extreme heat and extreme cold; then throw in every thing in between. A few months ago, where I live it was -35C and just last week it was +30C; that doesn't add the wind chill or humidex factors. Remember that for a good portion of the year we get cold, wet, miserable weather and that is the hardest to keep dry and regulate your core temp in. I'm not saying to put yourself in all those extremes, the Army will give you the equipment to deal with it but learn about living in them and try to adapt to some of them.