Warren Buffett says that you should only buy shares in those companies you would feel comfortable if they were no longer traded on a stock exchange and you had to hold them for 10 or 20 years.
Evaluating something with a time horizon of 10 or 20 years improves your thinking by adding a layer of objectivity and reducing the impact of short-term events. Consider an investment opportunity in a hotel at the Kenyan coast. If you evaluate the prospects for beach tourism over the next few years, investing may look very risky given the current economic slump caused by our politics. If you consider the prospects over a 20-year period though, present politics fades away and you emphasize factors like economic growth, increasing disposable incomes, a bulging middle class, better infrastructure, and the steady improvement of our institutions.
Yesterday we celebrated the heroes and heroines who fought for our independence. They could not have been certain that they themselves would live to see independence- and many of them did not. But they knew their actions would reverberate through time. Celebrating them is also celebrating long-term thinking.