You are in an empty white room. Just you in a stark, small empty space. With nothing to do, nothing to entertain yourself with. You fall asleep eventually only to wake up to the same bleakness as before.
Now an empty notebook appears in front of you. Then a pencil.
You now have something to do. You are not bored anymore. Having some writing/drawing materials makes a big difference. You can now journal your thoughts, draw your imagination and document world-changing ideas you are going to implement when you get out.
You don't live in this white room.
Your world is at least a million times more interesting than an empty room with some writing materials. So quit thinking there isn’t enough external stimuli. If you are constantly searching for external solutions to boredom, perhaps you need to start looking inside.
All sorrow has its root in man’s inability to sit quiet in a room by himself. — Blaise Pascal
Next time you feel bored. Think of the white room.