Jesus man, I'm in my early 20's and even I don't make sure to put my phone in my pocket just to go pick up the mail. What could possibly be so important that it couldn't wait a whole 120 seconds?

Nothing - but the same habit also compels me to carry my wallet & keys everywhere I go as well. It costs me nothing to carry it, and there are times where I've returned to my apartment after stepping out for a minute to find myself locked out.

How do you get locked out if you carry your keys with you everywhere you go?

An always locked door?

But he has keys with him, so he's by definition not locked out. Maybe I'm reading into it too much.

My door locks automatically when its closed - so when if I were to forget my keys, I would get locked out (which has happened, which is why I always carry my keys).

Look, I'm not advocating illegal lock-picking here, not at all. But you may want to take a look here: http://www.artofmanliness.com/2014/11/19/how-to-pick-a-lock-...

I make it a habit to never leave without my phone so that I don't forget it anywhere. Even when I get up from my desk to get water 10 feet away.

I do that with my wallet and keys. I rarely take my phone out of the house though, and even leave it switched off for days or weeks at a time. I'm not sure what I'm missing out on by not having it available 24/7.

It's a very liberating feeling once you have 'trained' your friends and family that you are not dead nor hate them if a text goes unanswered for a few hours.

That is orthogonal to having a smart phone on you 24/7. I trained my friends and family not to expect instant replies (or me always picking up phone calls), but I use the phone also to read stuff, search for stuff, and note down stuff, so I do want it on me all the time.

I'm usually in the same place, and using my Linux desktop. I guess that's why I've always found it hard to get interested in phones: annoying devices with too-small screens, slow data entry and usually a locked-down OS with no updates.

I usually set mine on a table or whatever when I'm home, but if I need it to get my mail, I'd take it and it's not a big deal.

You think that is healthy?

Not OP, but... yes, I think it is - at least if you use your phone for anything else than just reading trivia and socializing with people.