How to be grateful ?

I've a alot of stuff but I'm not satisfied, I know I've a lot still I have this thing idk I just keep wanting more and more, and I don't know how to be more grateful.

I do know I've a alot of stuff for which I should be very much grateful, but when I see people my age having more stuff I feel the wants of those stuff too.

I'm well aware that I have to be grateful for things but in my heart I feel so greedy and needy. I know I've enough, but it doesn't feel like it.

I try to be more grateful but it's just from inside I feel things aren't enough for me and I keep thinking about more and more and more.