You don't have to run. Play tennis, cross-country ski, meet a friend for racquetball during your lunch hour. Find a way to work your body hard on a consistent basis and don't decide if you're an optimist or a pessimist until that's the routine. You may not believe how much your outlook on life changes.
People get really discouraged when they've dated a few people here and there and still can't find anyone who is "right" for them, or when something goes awfully wrong in what was supposed to be the perfect relationship. here's a list of important reminders we tend to forget when we get lonely, lack a love life, or are tired of dating.