I think the answer to your question depends on who you ask. Growing older means more experiences, a stronger sense of self-confidence, but with fewer remaining years. Like everything, there are inherent positive and negative aspects with aging. Reaching the statistical probability that more than half your life is in the review mirror, leaves one feeling like its "now or never". Depending on personality, personal preferences and values, the realization of mortality can be motivating. Those areas we neglected in youth are often approached with urgency. With aging, many people "get real" and do the things they never had or made time for when they were busy taking care of their responsibilities. Retirement brings the time to fulfill dreams, such as travel, greater involvement with family, hobbies, further education or leisurely relaxation and fun.
Unfortunately, as we age, our health becomes more fragile and, often, illness can waylay the best laid plans. When I was young, I saw many neighbors look forward to retirement, only to develop devastating illnesses that changed their plans and quickly took their lives. One neighbor and friend who had just retired, developed a blood clot. Long story short, after being air-lifted to an excellent hospital, he had a reaction to the blood-thinner used to dissolve the clot in his foot and ended up a double-amputee. Depressed,but not defeated, his car was fitted with hand controls that enabled him to drive and he was beginning to get out among friends when he developed spinal cancer. He and his family suffered tremendous loss with his premature, agonzing death shortly after retiring.
As we get older, we all witness these kind of sad stories. There are no guarantees in life. No one knows how or when our turn will come. With age, we come to appreciate the things we once took for granted, like a good night's sleep, feeling well, a beautiful day, a summer rain, our dog's unconditional love, a grandchild's laughter, a spouse or lover's smile. The undeniable reality of our mortality creates appreciation for what was once considered mundane, boring or routine. Rather than the frantic pace of our youth, age savors, making everything good even better.