Not having a car (always living/renting in walking or biking distance of my work)
Moving in with my partner straight out of college so we could split expenses
Moving (with partner) to a low-cost-of-living city for the first 5 years after college
Putting most of my medium-term and long-term savings into low-expense-ratio, passively managed index funds starting in my early 20s
Buying almost exclusively second-hand clothes, furniture, and cookery
Borrowing all desired books (and many desired movies and TV shows) from the library
Only buying games when they are bundled or otherwise on steep discount years after release
Pirating any other media in which I'm interested if its distributors make it even remotely difficult for me to buy it at a reasonable price
Planning all dinners in advance every week before grocery shopping (leads to almost never eating at restaurants or ordering takeout, and almost no food waste because grocery list is based on actual meals)
Now, if I had to choose the best financial move out of that list? Probably the index funds. Though not having to pay for a car (or car insurance, or car registration, or car repair and maintenance, or parking, or fuel) is a close second.
I'm contemplating moving even further towards the lifestyle you have but I struggle with balancing "live for today" vs "live for tomorrow". In some ways I think we live too much for today, we rarely wait more than a month or two with buying whatever we feel we "need". We go on vacation abroad every other year at least and do activities monthly that most other families in our neighborhood do maybe yearly or quarterly. Partly because we have much higher income than our neighbors but we could of course save more and if we really buckled down we could likely by financially independent in less than 20 years.
How do you balance and how do you think regarding these matters, what's your philosophy?
I've never felt I'm not living for today. Admittedly, most of what I want to do is consume a variety of media within the comfort of my home. But we also travel abroad every other year or so, and that's probably the biggest 'entertainment' expense in our lives. If we need a car to visit someone or somewhere outside the range of public transit or biking, we just rent one for the weekend (probably happens about once a year). We don't have to hesitate before choosing to do that because we know we're living well within our means the rest of the time.
The thing is, once you're in the habit of doing this stuff, it doesn't feel like an imposition. It's just the way your life works. It was actually a bit of a struggle to remember all of those points when I was writing up that list yesterday, because it's all just natural to me now. There are probably a few more things we do along these lines that haven't occurred to me.
And at that point, the savings are just a natural choice for what to do with all the surplus money. It's not even 'living for tomorrow.' It ceases to be an either/or situation. It's living for today in such a way that you can continue to live for today throughout your entire life.
Also, there are a huge number of non-financial benefits on offer here, too: walking and biking at times you'd otherwise be driving is excellent for your health; planning meals allows you to choose healthier options, cut down on red meat consumption, etc; meal planning, buying second-hand goods, and not driving reduces dependency on online mega-retailers, international sweatshop labor, and environmentally harmful practices; making use of the library system indirectly supports its continued existence for folks who have no other options; and on and on.
Anyway, I wouldn't recommend trying to do all of this at once if it's all a change for you. I'd recommend slowly introducing each of these practices over time so you have time to get used to each in isolation.