According to Cleese, creativity can only happen in open (-mind) mode, when you are free from interruptions, distractions, unlike when you're closed (-minded), which is when you are at 'work' busy with phone calls, stuff to do and there is some pressure, anxiety, and tension.
Open mode isn't all - there are 5 important elements required too:
1. SPACE - undisturbed, quiet, where there are no interruptions, phones ringing, emails being answered, etc, which means no TV!
2. TIME - a specific amount of time, at least 1.1/2 hours, which includes say 15-30 minutes for winding down and getting calm - again no TV!
3. TIME - yes more time, once you've created an oasis of calmness, you can tolerate the slight discomfort that you may feel until you solve the assignment/issue creatively and get some work done.
4. CONFIDENCE - so that there are no fears of making a mistake because nothing is wrong so there will be no mistakes.
5. HUMOUR - this gets us from closed to open mode quicker - laughter helps us to relax and doesn't detract from the seriousness of the 'problem'. So laugh, giggle all you want when being creative.