I am 100% dreaming fiend.
Day or night, crowded room or utter solitude, I dream. I let my mind have a go at whatever is the issue niggling at my mind. As a wee lass I had incredibly vivid nightmares; the sort that would result in me waking the entire household. The only way to get to sleep and stay asleep was for me to embrace Guided Lucid Dreaming (GLD). It's not quite as hug-a-tree as some folks want you think. It's very simple, and it is the means by which I do all of my plotting, character creations, world-building, etc. GLD is my go-to method for fixing any story problem from plot-holes to flaccid conflicts.
How is GLD different from regular dreams or plain old *gasp* thinking? I'm no neuroscientist. I'm more likely to tell you it comes down to drool/no drool. Heck, I'm no New Age Guru either. I am, however, going to use a term the NAGs love to clarify my distinction:
Guided Lucid Dreaming is all about dreaming with intention. It's like telling your mind, "Go where you will as you will, but you're going on this Palomino with flaxen coat and chipped teeth. Oh, and poor thing is allergic to apples and hay too. Have fun." As the dream begins, you keep reminding yourself of the imperfect chuffing horse in order to keep the dream focused. Fairly soon, your brain accepts the restrictions, and moves forward with the Palomino and its flaws as your only tethers.
How do you dream with intention?
1. Pose the question to yourself -- Envision the issue with which you need help.
2. Hold the question in your mind -- If worries about the mountain of missing socks or the wholly inappropriate tirade of your boss try to intrude, mentally push those issues aside and focus again on the question.
3. Let your mind wander within the framework -- From the incredibly absurd to the horrendously practical, don't limit yourself. Your mind is downright magical. It will eventually present the solution.
You'll note I've said nothing about your physical state. For some folks, being still (aka, lounging) works best. For others, repetitive physical activity (aka, the monotony of running) creates the necessary mental quiet. Some folks need to be surrounded by external quiet to achieve internal quiet. Tuning out the external noise functions as a sensory "all clear" for other people. How you achieve your zone of internal serenity is up to you.
Once you've achieved internal serenity, frame your question, hold it at the fore of your thoughts, and dream.