Most of my teaching ideas come in the midst of every day life; in the shower, running errands, in meetings, as I fall to sleep, etc. Very rarely do I pray for something to teach on (and when I do, it's because I haven't gotten anything!). I'll go be with the Lord and ask Him what He thinks, how to lay it out and then we'll dialogue for a bit on what that looks like, what the best way to lay that out is, etc.