I would stop time. Thus, the day I had left to live would not end until I wanted time to resume. So technically speaking, I could live for eternity in that instant time was stopped. Eventually, when I would grow bored with my life, I would spend the next couple hundred years of my life (relevant to me, time isn't actually moving) removing the clothing of every single last human being on the planet. Once everyone's clothes are off, I would resume time with myself being in one of the most populated areas in a given area, possibly time square. I would just sit there and watch the hilarity take place as I am the only person wearing clothes in the whole world.