Steadily and purposefully purchase stock in the most successful companies. Today that may be Apple, Google, Amazon, etc. Also look for recession-proof industries. Once the money is planted let it grow ergo do not ever touch it. If you micromanage it like most investors you will simply lose. That is why computers do the work at the big firms now and why darts can many times beat senior investors with impressive titles.
Even though Apple is very expensive right now, every new device they sell is more expensive than the last but it sells tens of millions more. Thus current price does not necessarily dictate value. Apple today even is a great lesson in identifying good investments in the future.
In identifying new companies look for ones that are selling something profitable at a high rate. Always think, "What is selling out there? What is popular?" Do not be like most of us where we kept thinking in terms of the past while explosive trends happened right before our eyes. PAY ATTENTION to your reality throughout life. Never stop paying attention or get too distracted by work and home and such. Investing is a free second salary which requires zero hours of clocking in at work. That is why it deserves the same constant, vigilant attention that you provide to your job.
For additional investments filter companies that have had a stable or even increasing dividend for many years. That will help provide a more solid base among the products that turn out to be "here today, gone tomorrow."
Watch the long term as we all have a habit of getting caught up in the moment. For a stagnant economy, pressure builds up just waiting for a relief valve, like a simple change that sparks massive investment. Based on our history, by the time you are 50 you will likely have seen two periods of 8-10 years, one of stagnation and one of growth. You cannot beat history and due to certain factors the US keeps repeating it ad nauseam. Changes in the top marginal federal tax rates and any new regulation, such as for healthcare that affects business greatly (from 7-13% average of total compensation for Americans) can be significant indicators of what to expect in the short term.
No matter what the economic figures state, always see the glass as half full. The anemic growth from 2008-2016 kept stock prices low so it gave people the opportunity to buy more stock. This is going to have some surprising effects (more below.)
Not blowing it on new parts, 2nd house, strippers for
@rubbersidedown, etc
I'll delve into more details and factors if anyone is legitimately interested.
You are brilliant in living below your means and working and investing
until it hurts. While you solicited for advice, most people cannot give you advice because you are already ahead of them from an attitude standpoint.
I know quite a few people in their mid-forties thinking about Financial Independence Retire Early (F.I.R.E.). Some have your attitude and some got lucky in being in the workforce during this period where the corporations began automatically subscribing employees to the 401k on day one of work.
I know people around your age who are darn good at what they do and thus I figured passionate about work. They surprised me and talk like they are 50-60, telling me that there is no way they are staying in the workforce but are getting out as soon as they have the opportunity to do other things. (They do not have huge salaries and are not rich. They merely have attitude.) This is part of "pay attention to what is going on." If you think hearing for the last eighty years "I cannot afford that. I am on a fixed income." is bad, just wait. Social Security assumes that the entire population will pay in until they are 62. A massive portion of the population is now going to drop off, at least from their peak wages, far earlier in life than 62. Say goodbye to a huge portion of the SS tax base. So much for assumptions!
I mention SS because it behooves you to consider in your retirement planning that with the depletion of SS or hyper inflation if the government turns on the cash printing press, you should plan essentially for shredding your SS check and being in a position where you do not require it. Absolutely do not put the SS emergency stipend on line 1 as "Primary Income" on your financial spreadsheet like most of the population has done until now. That
choice is going to blow up in peoples' faces far worse than ever before.
The flip side of investment is that if salaried incomes that are taxed for SS plummet, the politicians could increase punitive income taxes. So if one is retired and pulling $15k out annually tax-free, because those are the rules that were
promised to us, well, promises can and likely will be revoked. You have possibly already heard of politicians wanting to raid 401k and pension plans! However, the investment route is the route to success for now.