So you aren't alone, I think most everyone goes through some form of work based isolation essentially if they do knowledge work (or have fuzzy endings). The key is to have a few activities you do outside of work that are scheduled and you enjoy. This forces you to do two things, one cut off work, and two interact with other humans doing something non-work focused. For me, I have found coaching youth sports is a great outlet that checks a lot of the boxes, e.g. people interaction, not work related and something I enjoy myself which forces me to be active too. I also love the water, just put me on or in water (pool, ocean, boat etc) and I can nearly instantly relax and enjoy myself.
Being outside is healthy, you need a "healthy" amount of sun time as our bodies use it for more than just Vitamin D, just don't cook yourself that doesn't do anyone good. I can seriously tell a difference in my mood and behavior even after just a week if I have been inside too much or we have non-stop rain where I don't get any sun.
* edit a couple of words
Entrepreneurship - it's literally part of your job to 'network'. But a lot of the people you meet are there to get something from others. It's vapid socializing, sort of like getting full with junk food or catching sleep at the back of a car.
Management is similar. You meet people as work. It makes meeting people not very fun especially when there's arguments and uncomfortable conversations. Some of us used to take vacations off after a week of meetings because we just want to get away from people.
Sales - you meet a lot of people who may or may not want to meet you. Some are really nice but because it's part of your job, you end up entertaining conversations you don't want to be a part of.
So by contrast, developers have the best social life. You can make node_modules meme and someone gets it. You can talk about fun theories - not too difficult like in academia, but the conversations aren't shallow either. You have acquaintances who sincerely enjoy your company, and not because they need something out of you.
My model for this is that I seem to have a fixed budget of sociability that I can either spend on meeting at work or on friends and family. It's pretty frustrating.
The main problem is that we can't switch modes or switch off - even temporarily. This happens to me often. I have been somewhat of a remote worker for the past 18 months, and I agree with you that out of frustration you are likely to choose to remain reclusive and indoors thereby making social (integration) matters worse if you don't do something to realign yourself.
Here are my known effective antidotes:
1. When you talk with others, make eye contact. Smile. You don't have to say much. I find that I have to actively force myself to look at the people I'm talking to. There is a lot of "communication" that takes place and cues from the eyes.
2. Make new friends or just acquaintances. I spend 4-5 days per week at the gym at exactly the same time in the day (10:30 am). This is probably the only social interaction I get on an average day outside of my family. By choosing a set time for the gym, I get to meet my own regulars who I've gotten to know over several months. The banter after friendly smiles is as important as a thorough workout for me.
2. Read fiction. I spend 1 hour a day reading well-written fiction. Away from the keyboard. Grab a nice cup of coffee, sit somewhere quiet and read. Choose a book of interest where the writer has full command over his/her language. I am currently reading an English translation of Antoine de Saint-Exupery's "Wind, Sand and Stars". I find reading the non-computer world helps to rewire my mind, now a specialised one-trick pony, back to a general conversational state.
Take care.
These days I get an infinite amount of pleasure from chopping onions, carefully cooking them until they caramelize, salting/spicing them ever so slightly, and watching the smiles on my friends faces. It's a definite and immediate payoff, and a visceral one at that :)
But then, if i'm on the computer i'm coding or doing something productive.
I don't read the news and I don't have facebook.
I'm i'm not "doing something" - i.e something that requires thinking, i'm out and about and exploring.
I don't watch tv either...i'm probably more sociable than most people to be fair...
I get depressed and demotivated...and stop learning if I don't get enough stimulation...
Being introverted and not being too sociable was probably a factor in me becoming a programmer to begin with.
But hey, it can definitely hurt your ability to socialise as well, especially if you don't have anything else to do outside of work/computer related activities.
That said