Why should Canada let Trump and the U.S.A. walk all over Canada without putting up a fight?

Why doesn't Canada sell its oil to countries other than the U.S.A.? 

Why doesn't Canada ban exports of Canadian softwood lumber to the U.S.A. and find other countries for Canadian softwood lumber? 

That would help Canada and help people in the U.S.A. who wouldn't then have to pay a 20% countervailing duty on Canadian softwood lumber.

If Trump and the U.S.A. want to be protectionist and isolationist, maybe Canada and other countries should just stop trading with the U.S.A., trade among each other, isolate the U.S.A. and let it use its own oil, minerals, milk, wood, etc. and fend for itself. 

Maybe Canadians should just boycott anything American, vacation outside the U.S.A. and shop and buy Canadian or anything other than American from Canadian stores.