In my experience, people older than me, at least the ones I've worked with, think that just because we are young our lives are easy, maybe because many of young people in this generation live in their parents house and some may still study and take life in a more relaxed way.
This is generalize, for many of us, life isn't that easy as we struggle with the lack of work and not being able to have a better future, many of us want to get out of our parents house and make our living, be able to have a house, build ourselfs a future.
Many of us doesn't have parents that can help so many of us 
started to work when still were very young.
So, my point in this, just because we are young it doesn't mean we have a easier life than many older people, maybe we are just so tired like them, maybe our body hurts just like theirs. Maybe we experienced some terrible things in life, and still fight and put a smile every morning, because life doesn't stop running!
Maybe we wake up just as tired and still go to work every day, not because we want but we need it, other way we just can't make a future.
Yes, older people has fighted and worked their entire lifes, but many of young, in theirs twentys started to work a long time ago.
We are not little kids, we have as many responsabilities as older people, so if your are older, be kind, we don't know everything, we are young, but we struggle as much as you did or do, we are learning and growing but so are you! Till the moment we die, we are still learning, every day!