I love this idea:
“Jeffery Fox […] recommends that you think daily for one hour. Not the unfocused, random thinking you might do in the shower or on your way to work […] but focused, committed thinking: planning, brainstorming, writing down ideas, testing hypotheses, considering a work problem, imagining the future, setting goals, etc.” 
I know that some people write in journals and diaries. Other take notes. Others create mindmaps and roadmaps.
For some ideas I buy composition notebooks and try to stick to one organized topic per notebook. Yes, it’s analog and I do this in purpose because I’ve noticed that I think differently when I write on the computer than when I write in other medium.
For other ideas I always carry a sketchbook. This one is for “open thinking” – where drawings, graphs, workflow diagrams, concept diagrams, thumbnails, writing, and other working ideas take place.
 Earned Value. (blog) : “Daily Thinking”