A generation or two ago, making this hike in your 60s would have been noteworthy. Not anymore. On that bright summer day, there were lots of people our age on the mountain. It’s the happy side effect of my generation’s Peter Pan attitude: “What, me grow old? No way.” We’re breaking the rules and having fun doing it. Along the way, we’re learning to love our age, whatever it may be. (The 21-day plan in Love Your Age is the life-changing reset every 40+ woman needs!) Here’s a sign of how much things have changed: I was reading a dog-eared book to my grandson the other day, and the grandmother in it had the short, Brillo-perm gray hair my grandmas wore. I don’t look like that, and neither does Zeke’s other grandma, who hosts a backyard volleyball game on Sundays that’s so cutthroat, I don’t dare play. Like Nora Ephron, I am no fan of my neck, but I don’t spend a lot of time worrying about frown lines and sagging skin. Frankly, there’s too much to do, and even if I were tempted, I’d rather spend the bucks on a safari in Africa than on a face-lift. Talking to my friends, I discover that while our outsides are aging, we feel beautiful in a way many of us never have before. The packaging may be getting a little tattered, but we’ve never felt more confident, more sure of who we are. So we patch ourselves up to whatever degree satisfies us and move on with our lives. And what amazing lives they are. Researching a recent story on late-in-life athletes, I discovered a platform diver in her 80s, a 59-year-old barrel racer, and a woman training for a 100-mile ultramarathon to celebrate her 70th birthday. Call it postmenopausal zest, as anthropologist Margaret Mead did, or generativity, the impulse—described by psychologist Erik Erikson—toward productivity, good works, even friskiness, which peaks in middle age. Whatever you call it, midlife and later can be the most satisfying time of your life. Happiness studies find that well-being hits bottom in the mid-40s but steadily climbs after that. More from Prevention: How To Be Happy [pagebreak] All this experimentation and fun can flourish because by midlife, it’s growing on the bedrock of a psyche that’s strong. We know who we are, and if we were once bashful, we no longer are. We no longer do things merely to be polite. We’ve learned to say no. The other day, I tried a new army-style drill class at the gym. As the instructor got in our faces, reprimanding us for not positioning our equipment on our mats precisely like hers, I thought to myself, I’ve spent 6 decades learning not to take orders from somebody else, and I ain’t starting now. I left that class and went straight to yoga. Maybe there’s a reason for those nasty little potbellies our bodies seem to want to grow: They focus us on what’s inside, the part that really counts. Whether it’s being a kind friend, doing volunteer work that’s meaningful, or falling in love all over again, it’s how we live life that really matters. It’s not that our lives are all rainbows and unicorns. At midlife, we deal with some serious stuff. I attended four funerals in a month. Our aging parents are losing their grip on life. Friends are coming down with diseases that we used to just read about. Lumpectomies, radical mastectomies, heart attacks, arthritis…all these things have happened to my friends. We learn how to grieve and how to console, finding our footing in another area of life. It’s sad work, but it’s critical, and it teaches us that we are strong. There’s a relatively new tributary of positive psychology called grit. It’s perseverance, stick-to-itiveness, resilience. At midlife and beyond, we specialize in it. I call it rosy realism. We’re taking our knocks, but we’re not letting them knock us down. We have the big picture, and we get the long haul. It helps to do things that make you feel ageless. I’m a cyclist, and every year on my birthday, I ride my age. So far, not a problem; I can see myself logging 70 miles at age 70. But 80 miles at 80? Less likely, but I refuse to rule it out, and that keeps my outlook young. Likewise, I challenge myself to do at least one scary thing every year: rock climbing, giving a speech, driving on a racetrack, rafting the Grand Canyon. As we get older, jumping out of our comfort zones adds exhilaration and fun—and reminds us that we need never stop growing. The other day, a friend asked me what the happiest time of my life was. My answer was quick and ardent: Right now. I hope to give the same answer 10, even 20 years down the road. More from Prevention: 50 Things That Get Better With Age