Effective October 17th, 2018, cannabis will be legal in Canada under the Cannabis Act.

Here's what you need to know:

To buy, possess or use cannabis, you must be of legal age (that's 19 in Ontario). Selling to or sharing with people under the legal age is strictly forbidden.
The only place to buy legal cannabis for now is online, via the Ontario Cannabis Store. This means that street dispensaries will remain illegal.
You can possess up to 30 grams of legal cannabis.
Legal cannabis can be distinguished from illegal cannabis, because it has an excise stamp.
Medical marijuana will continue to be provided by health care practitioners.
Your weed needs to be stored away from children, youth and pets.
Driving high and working high remain illegal. This is because cannabis can impair your ability to operate vehicles and equipment safely.
You won't be able to take any weed across the border. This applies to all countries, irrespective if cannabis is legal there or not. You might want to be extra cautious when travelling to the US.

If you are worried that legalization will negatively impact your frequency or amount of use of cannabis, consider the following suggestions:

Try to identify the feeling that makes you want to use. Many people use cannabis to self-medicate symptoms of depression and anxiety. It might be a good time to look into treatment options and support groups.
Reach out for support. Everything is easier when loved ones are able to assist you. Try it - people love being asked for help, whether they are family members, friends, or professionals. I'm always happy to speak with you, too, and might be able to point you in the direction of additional support.
Reducing or stopping your cannabis use usually takes more than one attempt. It's especially hard when you surround yourself with other users.
Seek out sober environments and make non-cannabis related activities and people a priority.