For myriad reasons, many seniors and retirees are staying in or jumping back into the job world. By 2030, nearly 40% of people ages 65 to 69 are projected to be working, according to the U.S. Bureau of Labor Statistics. Reasons include staving off boredom and loneliness, saving for big expenses, paying off debt or simple financial necessity. As “8 Signs That It’s Time for You to Unretire”…