I was convinced I became an adult when I turned 21. But now, I'm certain that turning 65 was the watershed moment that finally made me grow up.

Don't get me wrong. I'm pleased as pomegranate punch to be 65. But I realize I need to work on my playbook for life after 65.

"We enter this phase of life without a playbook or anything equivalent to institutions like elementary school and college that prepare youth for adulthood," said James Firman, CEO of the National Council on Aging. "There's really nothing to prepare us for the transition to this next phase of life."

If you're looking to prepare for your next phase of life, consider these suggestions:

• Evaluate your diet. Try to reduce the amount of red meat you eat and opt for vegetables, greens, grains and fruit instead.

• Bone up on Social Security. Check to see if your city or county offers free seminars.

• Consider enrolling in Medicare Part A, to cover hospitalization expenses.

• Double up on checkups. "Age 65 is a time to proactively visit a geriatric physician instead of just going when you're in trouble," said Dr. Ardeshir Hashmi, director of the Center for Geriatric Medicine at Cleveland Clinic. "Don't wait until things get to a point where you're in a cycle of being in and out of the hospital all the time."

These appointments should last longer than the standard 20 minutes, so patients have time to discuss what's on their minds. Older patients who do this regularly tend to require "minor tweaks" instead of major repairs, said Hashmi.

• Schedule annual visits to the dermatologist, ophthalmologist, and visits every five years to the gastroenterologist. "Establishing a coordinated care team becomes more important at 65," said Jean Setzfand, senior vice president of programs at AARP.

• Get up to date on your vaccinations, including for pneumonia and shingles vaccine.

• Review your financial plan.

• Serve your community. If you already volunteer, see if you can bump up your time.

• Stay active with daily exercise and stretching.

• Stay connected, and not solely via electronic devices. Cherish the friends you have, make new ones and, if you can, banish past grudges and re-establish contact with pals from the past.

• Get your paperwork in order.

• Live with purpose. Turning 65 is not just an extension of middle age. "It's a new stage of life that reminds us we don't have forever," said Firman, who believes that the real purpose of aging is to make the world a better place. "Life is a gift," he said. "Success in old age starts with an attitude of gratitude."