Earlier quoted context omitted.
My happiest period with relation to work was similar, laborious but satisfying because I got something done every day and didn't have to think about it after work. When you're writing software, it's hard to turn off the switch (I think especially if you find software development itself to be an interesting subject) when you leave the office. It's hard to not think about the design, the thing you'll do tomorrow, conti…
Working for a big software company (thousands of software engineers under one roof) will make that off switch work again. You'll leave the office and instantly not care or think about anything you do until you cross the threshold the next morning. This is the positive side (along with the salary) of being a tiny cog with no power to influence broader design decisions.
Worked at Microsoft and now I’m at one of the big AAA game companies (working on their online services side, not games directly) and both were/are very stressful. High expectations of commitment and personal investment in what I do.