The company's long-term prospects remain bright, even after recent challenges.The old proverb "patience is a virtue" is very true in the world of investing. Investors who aren't scared off by a struggling stock, have the ability to see the company's long-term potential, and decide to buy and hold on for a number of years could reap the rewards.And today, UnitedHealth Group (UNH 1.56%), a health insurance leader that's faced challenges in recent times, may offer investors this opportunity. From a federal pro ...