If you could chose how long you want your lucid dream to be tonight, out of these options.
* Don't have one at all
* 20 minutes
* 1 hour
* 1 day
* 1 week
* 1 month

You have to stay in your lucid dream until the time is up. You can't wake up prematurely. Keep in mind if you chose the longer options, how mixed up you'll be when you finally wake up to reality. (you can't do whatever you want)