As summer passes, we're reminded how important vacations are. In part, it's about happiness. There are certain abilities we need to be happy: and they're falling into disuse. You can relearn them on vacation.
For instance, the ability to sit and do nothing! Watch the waves, the sun go down. This experience of deep absorbtion is what allows us to feel deeply.
Another neglected ability is the ability to be leisurely: to take your time, to notice, to appreciate. In particular, this is important for relationships, and good relationships are at the heart of happiness. You can't have good relationships if you're harried and distracted.
And finally, the ability to reflect: to take stock of your life and ask if you're living the way you want. This is something we usually do on vacations, and may neglect if we never escape.
So you can revive these basic abilities when you go on vacation.