I am not quite sure where I learned about third places - I think it may have been Virigina Postrel. She is an author for whom I have very strong positive and negative views. Her book "The Future and its Enemies" is an interesting, and parts are very good and parts are not so very good (she gets ecology/Ecology wrong). She has an interesting analysis on why some of Al Gore's social policies are not much different from Pat Buchanan's.
But third places - first & second are home and work. Third places are the corner bar. When I was at MRU and lived in the inner city/working class part of town, there was one on every corner. Sometimes they are churches/places of worship. Bowling Alleys. The small pocket of wilderness within 20 min of home or work. The existence of third places and support of third places and acknowledgement of third places means that there are times when you want to be somewhere other than home and work. And that you sometimes want to be away from your co-workers or your family (categories that are more fluid in early adult life). Or that you have people who are not co-workers or family, with whom you want to spend time. These are called "friends".
I surely struggled with this for much of my younger life. When you have little children who depend on you, the very concept of third places becomes foreign, or a dream, or not something there is even room to think about.
I think that as much as we, at any age, at any stage, can make room for even a small amount of third places in our life we will live better lives. Yeah, yeah, yeah, its easier for me as a blue hair to recommend this. After all, I've got tenure. Yet, one of my biggest challenges right now is helping younger faculty. I think that pulling all-nighters after you are 25 is ridiculous. I think taking an hour to go for a hike is not. Its a marginal return to effort. Its this. Finding the third place you need is a way of shifting those curves from B to A. Go read "From the Mixed-Up Files of Mrs. Basil E. Frankweiler" again. Or for the first time.
I have a third place. It is a wonderful Grown-Up-Bar. They serve very good wine by the glass, which is better for my morning work than their very good scotch by the glass. Yes, I make a grown-up salary so buying a glass of wine for me is not issue. But best of all, I have friends who live near by. They know I hang out in the GUB. They sometimes come by. I have invited my young colleagues to come and have a glass of wine, or if they don't care about carbs, a Good Beer, with me. We can talk. It's mixing 2nd place with 3rd place, but it lets me help them a lot. Its one way I can signal to them that they are real people to me, that they are worth my time and effort. It means that they are more likely to believe me when I say the world is not ending tomorrow. That tenure is not impossible and that their science is good. It means I can say "I am Groot" and people actually smile, and sometimes laugh, and no one compares me to their grandfather.