I'm 28 years old, working for 4 years. I talked to a 26 year old colleague who knew a lot of different cultures and countries because of traveling, and has so many creative ideas. How do I catch up?

You will not regret when you check your amount of savings 10 years down the road

I believe everyomne of us has their own priorities and their own timeline. When you look at others who are well travelled, it doesn't mean they are doing good in other aspects of life. They might seem more learned after experience the different cultures etc. but who knows they might be living from hand to mouth just to feed their travelling desires. To be truly happy is to know when to stop comparing with others and be the best version of yourself. Do what you like, like what you do. Good things will surely come to you, don't fret :

Don worry, the countries will not disappear over night. You can watch some youtube videos on those travel vloggers First. once you had earned enough money, you can then go and experience the country first hand.

Apart from a lot of the great answer given, another way would be to go to meetups with foreigners, there you will be able to meet new people and understand about the different cultures and exchange ideas.