If you don't do it, you'll never know what would have happened if you had done it. (Ashleigh Brilliant)

Winston Churchill

If the Almighty were to rebuild the world and asked me for advice, I would have English Channels round every country. And the atmosphere would be such that anything which attempted to fly would be set on fire.

Have a look at past verb forms with present or future meaning. Which conditional should I use? - all you need to know; and a quiz.