When I vape, I vape! Like right now, I've been chain vaping for an hour or so. I just love it.
When I don't vape, I just don't. At work, even going out sometimes, I just... don't feel a need to vape at regular intervals. That's one of the things I love most about vaping. I feel free. Coming from a pack a day smoking, when I'd end up many times in that "I need a cigarette right now" situation, this is probably the best thing about vaping.
I'm not worried at all about my vaping, but that's just me. Maybe I should be worried. But I read A LOT, reviewed tons of literature, gave it many hours of thought and I can't find any reason to worry too much.
I doubt vaping will be proven to cause cancer.
Certain plastics (from poorly chosen bottles, who knows - cartomizers, drip tips even) might lead to a tiny amount of carcinogens in the vape. Nicotine is not a carcinogen, but has been shown, in the lab, to contribute to tumor growth if such tumor does exist. It's not enough to draw a clinical conclusion, but maybe worth keeping in mind. Flavors - there's no telling, but most of them have been shown to not be 'heavy' carcinogens (mutagens, that is). But if they, and other stuff in the vape, do indeed cause constant "irritation" (inflammation, tissue damage and constant repair), then they could theoretically contribute to cancer. However, a couple of hundred other substances found in a regular diet are more carcinogenic than what our vapor would be in the worst case scenario.