Creativity is a very important aspect of keeping a balanced mind. The more balanced your mind is, the more able it will be to perform the tasks you ask of it. And don't think "creativity" has to be writing a novel or painting a masterpiece. The brain (and 'spirit') can benefit from simple and small adventures in non-linear thought and action.
This video about respecting the creative process and accessing the right frame of mind to utilize the experience of creation, will give you some insight into the value of allowing the journey to be as, or more important than, the destination.
I'd also like to point out that the lessons Eric Maisel uses are equally as valuable for cleansing your mental palate before undertaking any new projects. You don't need the pretense of "thinking outside the box", you need only to open your mind to the concept that the process of creativity not only gives opportunities to learn from your mistakes, but by not focusing on perfection or the shortest route from "A" to "B", you have the chance to explore all the options that present themselves. You're likely to find that by removing the pressure to perform or think a certain way, you actually sharpen the mental tools that you have and may even find other, more valuable uses for the tools already at your disposal.
If you continue to follow a prescribed path, you will always not only end up in the same place, you will only ever see the same sights from the same perspective.