Imagine waking up to hear that what your company has been making for more than 100 years is now considered unhealthy. That’s what it’s been like for General Mills’ Ken Powell. Analysts applaud cost cuts, efficiency improvements and revenue growth due to changes to its breakfast cereal sales and investments in organics. Now his challenge is to reenergize Yoplait yogurt, which has lost ground to newer Greek-style yogurts. Even so, General Mills’ stock continues to keep pace with, if not outperform, many others.