Sometimes setting extreme limits to ones playing and composing can be very effective. With instrument you must really think technical things and break away from common patterns and fingerings. When composing, with limited material you really had to think musicality and musical solutions.
Actually extreme limits does unlock creativity.
I made a little project with guitar. I made new little solo guitar piece every weekday. First limit was time. Tune had to be completed in twenty minutes – no more. And every day. One week week was limited technically: first week was in open position, second A-,D-,G- and B-strings only. Every day there was also another limit – some musical thing: modes, chords, arpeggios… Every tune was also made public – the most difficult thing was seeing myself playing not so polished – overproduced – musical material.
Antti Sunell Music Blog 
Jack White often references limits that spark creativity in his music. ”Little Room” as an example. Thanks for the inspiring post.