My answer absolutely has to be “Tell Me” by Groove Theory (1995).

There is something completely timeless about that smooth, mid-90s R&B production. The moment that crisp drum loop kicks in alongside Amel Larrieux’s effortless, breezy vocals, any stress instantly melts away. It’s not an aggressive, high-energy “happy” song like “Walking on Sunshine,” but rather a mellow, golden-hour groove that just makes you want to lean back, smile, and bob your head. It carries a perfect, nostalgic warmth that instantly resets a bad mood.