Simply No one can... not even the Extra Brilliant People.
No one can force his mind for new ideas because ideas come when your mind really wants it.. And your mind seeks for new ideas when it is in a stress free environment.
I usually get new Ideas when i'm bathing - My Bathroom is my Idea Generator and i get some awesome ideas daily while bathing.
I get Ideas when i'm in my bed to sleep - Before i go to deep sleep, i encounter with some random ideas... Sometime it takes away my whole sleepy mood.
The reason, i get new ideas at these two particular place because of the stress free environment. In other word, you can say that a Stress Free Environment is the fuel of Creative Idea Generator.
But ideas stay in my mind for a less period of time, so i quickly note them down on a notepad or a mobile device (whichever i find near to me).
Ideas comes in bulk, so it is difficult to remember every single idea. Therefore, noting of ideas quickly when it strikes your mind, is the best way to retain it.
When i get new Ideas?
1.) Bathing Time
2.) Sleeping Time.
3.) Coffee Time (Extra)
How i keep them Alive?
1.) Noting it down in a Notepad.
2.) Noting it randomly in a Whiteboard.
3.) Note down the ideas in Mobile Devices.