Sit back and hum. Hum while strolling, hum while reading. Hum a tune, hum a sound. Hum. The act of humming boosts the immune system. It's a natural "mood" enhancer.
It's also great for attracting attention - and for meeting people.
The best hums are original, uncrafted expressions, straight from your casual mind. The sounds drift up and resonate as companions to your silent thoughts. They emerge unforced, unplanned, and gracefully from intuition.
For the hum to be successful, it should be almost subliminal...just below the threshold of conscious awareness. Not too loud, not too soft. Other people next to you should barely hear it...or, perhaps, when they do, they think it's their own imagination.
If the hum is positive and pure, strangers sitting next to you may lean noticeably in your direction - as if wanting to hear more. The best place to hum is the cafe of a bookstore like Barnes and Noble, while drinking tea or latte and browsing a good book. If the background music is temporarily shut off, so much the better. The melody from your calming vocal chords shall provide the ambience from within, embracing and nurturing everyone in the room.
Try the hum. Do it in private, do it in public. Do it often. It's the sound you first heard as an infant, the vibration you felt when you were often nudged against your mother's shoulder.
Whistling is good, too. But humming works better. It's less invasive, more welcoming, and more personal.