Though many workers look forward to retirement and the opportunity to break free from the daily grind, it's also a worrisome prospect, particularly from a financial perspective. But of all the various retirement concerns today's older workers have, the two most pressing are future healthcare expenses and changes to Social Security that could reduce benefits, according to the Insured Retirement Institute.If you're worried about paying for medical care as a senior while losing some of the benefits you might one day come to rely on, you're clearly not alone.