Restriction forces creativity.
As a writer, I'm very familiar with the utterly terrifying "blank page". Over the years of trying to be an artist, I've found many ways to deal with the fear of a blank page or the "writer's block" that happens from time to time. I'm not going to say that creative blocks don't exist, they definitely do. But I am going to say that they are not as big of a deal as we often make them out to be, and if we recognize them, and shift perspective, we can knock them out of the way pretty quick.
One of the ways I tackle creative block is to impose a restriction on what I'm doing. I find this to be an efficient method of reigniting my passion for photography. We also talked about this idea for awhile at the photography workshop I recently attended, it was really interesting to hear everyone's different perspectives on it. I think everyone agreed that it is a beneficial practice.
A completely blank canvas can be terrifying. So, instead of starting with nothing, I pick a restriction. In the photography realm, I'll limit myself to one lens, or black and white, or a particular colour or shape to find in the environment. There are so many ways to add a restriction to your photography. All of them will improve your skill level once you intimately understand how to work with it. Some other examples are:
Pick one camera mode: Full Manual, Aperture Priority, Shutter priority. If you usually stick to only one of these modes, try another one. Read up on it, and start shooting in it.
Pick one shutter speed, and see how you can adjust other settings on your camera to get what you want at that speed.
Pick one aperture and watch how that affects what you produce.
Shoot in black & white for a week, you'll learn to see light and colour differently.
Shoot on a single lens, use your feet to do the rest of the zoom work.
Look for a specific colour or shape in your compositions.
Shoot only in portrait orientation, or landscape orientation for a while.
Find a photo you like, and try to figure out how the photographer made it happen, then try to recreate the same idea for a while. Your own style will show through.
There's this book by David Duchemin, The Visual Toolbox: 60 lessons for stronger photographs. It's a fantastic collection of restricted assignments that force you to look a little more closely, and thing a little bit harder about how you take photos. It's definitely worth looking at if you want more challenges to improve your photography skills.
Having a restriction forces me to be more creative about what I produce. It also helps me familiarize myself better with a technique or piece of gear. A few years back I had wanted to sell my 70-300mm sigma lens. I had it in my head that it was a shitty lens, it didn't focus well, and it wasn't long enough. On a whim, I told myself that I couldn't sell it until I'd spent an entire month shooting with only that lens. At the end of the month, I had a whole new appreciation for that lens and its capabilities. It turns out the limitations weren't the fault of the lens, they were my lack of understanding.
So give yourself something new to learn, challenge your usual way of viewing the world, and let me know how it works out for you. My latest restriction has been to challenge my daily photo by making it a self portrait every day instead of just a photo.