NEW YORK ( TheStreet) -- "Find your inner speculator," Jim Cramer told his "Mad Money" TV show viewers Thursday, as he dedicated his first segment to the art of the calculated long-shot. Cramer told viewers that he's always preached diversification, staying in a mix of stocks to minimize their downside risk. But Cramer said that he also always preaches speculation, picking one stock with huge upside potential to help keep investors engaged in the markets and excited about investing. One of those speculative picks paid off big today, he said, which is why he encourages investors to "stay in the game." That speculative winner was that of Vivus ( VVUS), a fledgling drug maker that today received approval for the first weight-loss drug to be approved in over 13 years. The news, a surprise to many, sent shares of Vivus up over 78% today. But was Vivus really a long-shot that no one saw coming? Cramer said that while many on Wall Street viewed Vivus as a loser with plenty of risk, those who did the homework on the company saw a different story. He said with the obesity epidemic in the U.S. growing rapidly, the FDA was under pressure to give doctors something to combat the problem. This was not the case 13 years ago when the last weight loss drug, phen-phen, was approved. Cramer called investing in Vivus a calculated long-shot, not a wild speculation. He said the stock's story should be a lesson to all investors that sometimes betting big pays off big. He said investors need to stay with the tried and true stocks, those like IBM ( IBM) and Procter & Gamble ( PG), both of which enjoyed small rallies today, but having a speculative stock like Vivus makes investing all the more enjoyable.