Each and every space that you have ever inhabited in your dreary existence till date, that you are currently inhabiting in the persistent continuation of your dreary existence, or that you dreary existence will ever deem fit to inhabit, has never been, is not and will never be yours. All spaces are common spaces.
The spot you were just standing in on the road has already had a number of vehicles and people pass through it, not to mention the occasional holy cow. The bus seat, even the toilet seat you sat on this morning has since been warmed by other posteriors. The cigarette butt that your lips so greedily agreed to get burned on is also being wrapped by other lips. The bed you slept on so dreamily will soon welcome another body, solo if you're moving house, shared if you hook up.
Even you yourself are common space. Every bit of your own body that you touch or feel, in whatever desperate attempt to feel loved, relaxed or wanted, will also be prey to the commonality that envelopes you. If you hook up, somebody else will be the predator; if you remain "never been kissed", then your other hand is always ready to play the part.
So what is yours and only yours then? Your email inbox? Bah! Other people's mails share common space. Your thoughts and feelings then? Maybe your loneliness, depression and sadness? Friends - physical, virtual (blog included), alcoholic, real, imagined - will make sure that you share that as well.
Your ideas. Your creations. These two are yours for as long as you wish, but only as long as you keep it to yourself and don't let anything from the outside world come within interplanetary distance.
Ideate. Create. It doesn't matter what - the answer to ending war, hunger and poverty, or another personality or imaginary friend. Ideate. Create.