You do not have to be Chatty Kathy like I am (my husband says the one thing he loves about me is how I make friends in the bread section) and engage in a long drawn out conversation with someone. JUST.SMILE.AND.SAY.HELLO. and keep on stepping. I mean, you probably burn about 5 calories and work some facial muscles that need to feel the burn. And you have to admit that when you do smile and it is genuine, you do feel the burn, and it's nice.
Don't expect anything in return, and if you are uncomfortable, find older people to smile or speak to. There are so many of our aging people who live alone and have no human interaction other than going to the doctor or the grocery store (and my personal opinion? I think that's why our elderly spend so much time at the doctor or in the grocery store, just to have someone SPEAK to them). Really, look at how few items they have in their baskets, or look at how long they hold something and read it and kinda look around hoping someone will stop and say "hey, that's a good product, how do you like it?" in hopes of striking up a conversation. It's nice to have pets and all to talk to, but sometimes it would mean so much more if someone could actually engage an elderly person's mind. They have so much to share, and since Ruthie is gone (almost 14 years now), I appreciate the time I can spend with someone of age over a bag of rice or a loaf of bread. I mean, it's just a few minutes of your life, and they will treasure it. And so will you.