Quitting your job to start a small business could be one of the biggest — and scariest — decisions you ever make. 

But if you're Jim Koch, the founder and chairman of Boston Beer Company, it could be as simple as choosing to be happy. When Koch launched the Samuel Adams beer brand in 1984, he was a 34-year-old Harvard graduate who quit a consulting job with a six-figure salary to brew beer in his family's kitchen using an old family recipe.