This recent term of school was more difficult for me than usual. I had incredible difficulty focusing on my work. Cigarettes really helped me focus, but I had quit them at the beginning of the term. Science tells us that apparently nicotine helps people focus. Check it out from an expert ... an expert on science:

The biggest problem with nicotine is that, actually, your brain works better on nicotine. It improves reaction time, it improves memory, it improves concentration, it helps you get through a frustrating workday. There are reasons why people hang on to nicotine. It’s almost the perfect drug.

I’m an ex-smoker, and I still miss it. I think I might actually have been more productive as a researcher if I’d continued to smoke, because I know it made my brain work better. It’s very, very hard to give up, and I’m very sympathetic.

Even almost 4 months after quitting, I'm still a little out of sorts - kind of relearning how to work and how to focus without nicotine. It's still worth it, though. Physically, I feel better than I have since I was 18 years old. I can work on the mental part.