I don't leave the house with a 'theme' in mind. It isn't stuffed into my gadget bag with the film, filters, exposure meter and notebook.
When composing a photograph, I do pay attention to the mood which the final print will convey. This in turn affects the exposure and choice of filter. As you might suspect, I'm methodical, working with a tripod and usually composing to an eventual height/width ratio.
For street photography, on the other hand, all bets are off! The recognition of a composition and 'shooting' it doesn't leave time to reflect upon 'themes.' [There'll be plenty of time to count my money when the game is over, as the old song suggests.] In the heat of the chase, it's me and my trusty ol' Russky rangefinder out there wingin' it.