The safest way to do this is to step out in daylight when the sun is bright. Take a brief walk. You will also get a boost of Vitamin D that will cheer you up. Interestingly, in Yoga there is a pose called surya namaskar (salutation to the sun) that is supposed to be done early morning when the sun rises.

Can I assume you mean without sunglasses on? Living in FL I wear sunglasses religiously, but am out in the sun daily.

Yes, at least for sometime daily, but not in blinding sunlight that can hurt your eyes.

I do not understand the assumptions behind this question. Can you clarify what you mean?

Is a red bulb enough or do you need a 670nm laser?

I hope this was a joke. Don’t shine lasers in your eyes. https://en.wikipedia.org/wiki/Laser_safety

For the love of all that’s dear in this world, please don’t use a laser for that.

If you’re in a DIY mood, you can easily pick LEDs around that wavelength and they would generate more than enough light to even cause damage (if close enough).

what assumptions? it was an honest question.