I'm a bit of a worrier, so if I can unwind, I find I'm more likely to engage in thought, read a book or have a conversation with someone I generally wouldn't talk to. In short,  when I have some time to myself, my mind wanders. This is where my inspiration comes from.

Where does this happen, usually? When I allow myself to go on vacation, I relax. When I take a shower, I relax. When I read a book, I relax. 

There are also certain activities and items that are symbols of relaxation. The very act of smoking a cigar is a commitment to leisure, whether it's an experience or a conversation. I also try, every month, to read a magazine about something I don't usually think about (e.g. interior design, gardening, fashion, religion) or a biography/non-fiction book. 

In conclusion, I find that inspiration happens when I'm able to break out of my everyday routine. That's probably when it happens to you as well.