The first step is not to resist change. Yes, the world is no longer the same as it was in the 90s or 2000s. But you are no longer the same as you were then. You have experience, endurance, wisdom. This is your capital. The world is changing - you can too. Without panic, without self-criticism. Just with openness: "I don't know everything, but I can learn and adapt."
Everyone has their own: some know how to listen, some inspire, some cook like a god, some always keep their word. Awareness of your own worth is the foundation of confidence. Make a list of your strengths. Seriously. Write down 10 things you are good at. Look at them - it's about you. And it's not outdated.
People who constantly remind you that you are "not the same anymore" - should not be in your circle. Look for those who see you as a living person, not a date in a passport. It can be a new environment, new friends, courses, online communities - spaces where experience and sincerity are valued.
You don't have to become an instabloger or learn all the features of ChatGPT. But mastering something new is like adding another muscle of confidence to yourself. Not in order to "be modern", but to tell yourself: "I haven't stopped. I'm still living, learning, trying."
Youth is wonderful. But only experience knows how to cope with real life storms. You have already been through what is still waiting for younger people. Your stories, your depth, your presence are something that no one can fake or buy.
The world may change, but your value is unchanged. You are not a "person of the past". You are a person with a history, strength and a lot of opportunities ahead. Confidence is not about how old you are. It's about how you feel about yourself at any age.