OT: Simultaneous Ideas or Procrastination Doesn't Pay

[Raellus]

From time to time, I come up with a germ of an idea that I think I might someday want to try to turn into a full-fledged novel or a screenplay. I write the idea down, intending to get back to it at some point in the future but nothing's ever come of it. I wrote this one down about four years ago.

"Rich people abandon sh*tty Earth and live on Mars. An umbilical of some sort connects them? Earth sucks- it's hot, toxic, overcrowded, etc. Mars is nice. Humans on Mars are genetically modified. They don't age or get sick and they're all beautiful or designer weird. They are called Homo-something (X-Men beat me to Homo-Superior). They travel to earth to "slum" it with lowly Homo-Sapiens. Maybe one of the 'normals' decides he wants a taste of what's up at the other end of the chord..."

That's as far as I got. I've tried writing fiction before, but I can't get past 2-3 pages before I get frustrated with myself and give up. Anyway, I saw this trailer for Elysium the other day and its uncanny how similar the premise of this film is to the idea that I came up with a few years ago. How do I get past the wall and start fleshing these stories out? I know that it's a long shot that I'll ever get anything picked up or published but how will I know for sure if I never really try?

http://www.youtube.com/watch?v=oIBtePb-dGY