For me remembering myself to take a step back often helps. Most of the time I am too focused on the problem at hand and overlook something I would recognize with some distance.

Try to view the problem from another angle. If you can, try to observe how your colleagues tackle these kind of problems. For me it helped to expand my "toolbox". Having options makes me feel more in control, reducing stress and tunnel vision.

Of course this does not always work. Take your time to improve, allow yourself making mistakes and, most importantly, be nice to yourself.