I believe everyone should travel to a foreign country at least once in their life, no matter their age. But I don't think you need to (or should) wait until you retire to do so. Society often tries to push the idea that you must "earn your right" to do anything fun by working all day, every day, for years before you deserve to do anything for yourself. When you're in your twenties, you generally have less responsibility and more time for yourself. It's okay to be a little selfish and book that trip you've been dreaming of, even if it's just during your weekend off work. There are ways to travel and still hold a full-time job, but once you get older and have more responsibilities (a spouse, kids, etc.) your priorities will shift. That's okay, however, your priority until you have those responsibilities should be you.
Your twenties are a very interesting decade, often filled with college graduation, truly being out on your own in the "real world," and figuring out who you are.
If there are things you want to do, then do then. Turn your dreams to reality (especially travel dreams!). If there's a will, there's a way. Sometimes you have to think outside the box and get creative. Sometimes you have to make sacrifices. Ask yourself if it's worth it - and in most cases, it will be.
When I was about to graduate, my main goal was to travel after college. My travel bug was acting up like crazy and I tried thinking of ways to go to Europe for a couple weeks with a friend. However, my budget didn't allow me to travel for even a short trip. And, my friend ended up having other commitments and could no longer go. So I got creative - I looked into travel jobs where I could live in Europe and also get paid.
With hard work, a lot of determination, countless emails, and an interview later, I got a travel job and was able to turn my dream of going back to Europe for a couple of weeks into living in Europe for five months. I had the opportunity to see so much more than I originally planned, got to live in Italy when I wasn't traveling for work, and met a ton of people that I wouldn't have met otherwise.
Instead of being a dreamer, be a do-er. And once you accomplished what you've wanted to do, dream up new dreams and do them too. By pushing yourself out of your comfort zone you will learn and grow so much. By continuing to do this throughout your twenties, you'll gain more life experience than you ever would have had you not at least tried to make those dreams happen.
Now that I've returned from my job overseas, I'm about to leave in a few days for another quick trip to Europe. I'll be working short-term for a couple weeks at a different company and I am beyond excited. I'll have a weekend of solo travel before I begin work (my first solo trip ever, and man am I nervous). I wouldn't have had this opportunity had I just sat there waiting for my dreams to happen. I had to make it happen! And it all started with a simple job application...
Whatever it is - taking that trip you've always wanted to go on, moving to a new city, or switching career paths to get your dream job - take action! And take action now. You only get ten years to be in your twenties. Don't waste a single second.