Can´t stress it enough that age is just a number, nothing else. But staying young has everything to do with your mindset. I have yet not had any age crises. Well to be honest some things do bother me with getting older, like how the body changes after 30 and that you have to work a little bit harder to reach your goals wether it has to do with learning a new skill or finishing a marathon. Everything else is just vanity.
Staying young, let me rephrase it, not becoming old has more to do with your mindset. If you approach new relationship with an open mindset, and stop thinking about what is limiting you ,you will stay young or at least ageless. Some people are so old in their behavior and thinking that they limit them self before even trying. If you embrace life and stop thinking about age you will become ageless. Remember that you set your own limits and become who you picture in your mind.
I never ever think about my age except when I seek employment but then I use it as a good thing, by thinking I am adding value to the company through my years of expericne. With other words they should see it as a benefit to have me around. Sure I will be the first to say I am impressed by young people and their fearless attitudes and drive. But I am pretty sure that had I been born in the late 80:is I would have had the same attitude and drive as they have. It has more to do with environment and when you where born.
Still, with this said, age is still a state of mind, and if you consider your self to be just you, with the will to be adaptable and like new things and be open to new ideas. Aim to be the best version of your self . Add spending time with people all ages, be curious about people and new things. Keep up-to-date with trends, never settle for anything less than really good and most of all smile allot, this will keep you ageless.