Figured this would help with many of you who have light or 'not deep' voices currently. It is 100% safe to do and will not harm your vocal cords over the long run.

In the morning, driving to work, going out for the night, whenever, say this phrase.

"Bing bong, ding dong, king kong"

.... Say it slowly, drawing out each word. "Biiiinnnnnngggggggg Bonnnnnnnnggggggg"

Do it three times over for the full thing. Afterwards, your voice will sound deeper and this should last about a day. You can do this every day and you'll see after a few weeks that it will begin to naturally sound deeper even without doing it daily. After a while though, it seems to fade back to normal if you don't keep it up.

Just a quick tip. I prefer to do mine in the car as no one can hear! haha