Too many times I use the excuse of oh well I don't have the time [to write], I don't know what to write, lah dee dah dee dah dee dah.
But what to write about? That's another roadblock I let stop me rather than just taking a running jump over the thing and landing where I may. What to write about? When you can't think of something, look around you. Any decent writer as at some level of observation skills, however minor they may be. Some people have them and that's what makes them a good writer and then others develop them through writing.
Mine aren't impressive by any means, and I'm not claiming to be a "decent writer" but what I'm trying to say is, when you don't know what to write about look around you. Take in your surroundings.
What's in the room? A floor, a ceiling, walls? Sure. Furniture? Yes. But everything has character. Everything has a story. Sometimes you know it and sometimes you have to suppose what it might be. Either way, there's always something to write about in anything and everything.
I have a similar philosophy for photography, something I able to delve into in college. It's in response to people that don't know what to take a picture of. The philosophy is this: all that is on the planet: every person, every place, every thing; surely, every inch of of space is a potential picture. You just need the right angle.
So then, in either case, there's no excuse to not do it, if that is indeed what you want to do; you have your motive. The means, a pen or pencil and paper, a computer and word processor, or even a typewriter if you want to get crazy. So, as long as you have the opportunity, DO IT! Write.
Your's In Writing.