Do you need a vacation if you love what you do? 

I used to think 'No', but after 3 years in a job I really enjoyed daily, I realized that I did need a vacation... And I've been taking one about every 6 months since then, even if it's just a stay-cation.

Your body and mind need some down-time to escape from the stress at work. And there IS stress, even if you enjoy it. I have never yet come back from a vacation and wished I hadn't taken it.

I havent had "real" vacation for years and feel perfectly fine without it. My recipe is to get "real" weekend almost always (if no urgency) and extended weekends for 3-4 days from time to time. I travel and enjoy simple life in these days (no work, rarely check email)

Yes. It interrupts the flow of things. This helps you get a fresh perspective occasionally and reduces the risk of burnout.