Around 1774, the former Chinese provincial governor Lu Yao provided a set of smoking rules in his book Yan Pu (Smoking Manual). In great detail he addressed the question of when to smoke (and when not to):

Do smoke: after waking up; after a meal; with guests; while writing; when growing tired from reading; while waiting for a good friend who hasn’t shown up yet.

Don’t smoke: while listening to a zither; feeding cranes; appreciating orchids; observing plum blossoms; making ancestral offerings; attending the morning court assembly; sleeping with a beautiful woman.

What a coincidence that I almost never engage in any activities that fall under the don’t category, but I do quite a lot of the stuff mentioned in the do list. Personally, I do however prefer to smoke while reading before growing tired from it.

(Source: 1493: How Europe’s Discovery of the Americas Revolutionized Trade, Ecology and Life on Earth by Charles C. Mann)