All of the posts above offer great advice. In my own experience, I attempted my first Whitney summit in 2005. I was young, not in great shape, and alone. I had a great playlist, stuck to the trail, remained vigilant of my surroundings (and myself), and summited with the help of others on the trail who paced me, chatted with me, and held my hair back as I dry-heaved near the summit (AMS at its finest). Since then, I've summited alone 20+ more times. In two instances, I brought friends along and had to pull ahead of them because they were slower, less confident, or sick. I prefer hiking alone now and I've graduated to flying myself over the Sierras alone just to get myself there! I say, "go for it!"...and don't forget a good playlist.
