One of the simplest ways I've found to get over a slight mental stumbling block, whether on my creative writing or non-fiction, is to move away from the computer. Often it's just the equivalent of a walk to the water cooler. For me this is to the fridge, or tap to fill my water bottle.
I can't count the number of times I've mulled over a section of dialogue, the assessment questions I need to create, or a topic for this blog with a white fog drifting through my head. I walk away from the computer and something comes to me. It's like magic.
I change my perspective and my thoughts change.
I like that thought on a bigger scale as well. Change the way you look at things, and the things you look at change.
For a while every time I've thought about my WIP I've thought about how stuck I am with the plot, and yes, I'm over the 'losing the plot' jokes!
So I'm taking my own advice and changing my perspective. After all I'm only stuck if I decide I'm stuck and don't try to move forward.