You can refer to the time in your life when you're young and everything is fresh and new as your salad days.
Older people are especially likely to talk about their salad days, when they were youthful and inexperienced — and maybe a little naive. The visual image that salad days brings to mind might be a little confusing, but its meaning is actually connected to the color of lettuce leaves. In 1606, Shakespeare used the phrase in "Antony and Cleopatra" to mean young, and green as a metaphor for something that's immature, brief, and fleeting.