Earlier quoted context omitted.
I would put money in a 401K or IRA that has a real penalty of withdrawing and takes time to withdraw as to deincentivize yourself from spending. Remove yourself from your financial equation. If you have a significant other and they are better with money have them manage both of your finances. You need to have money removed from your account and into investment accounts automatically before you have a chance to spend…
My one caveat is that you really want some savings that you have reasonably ready access to. As someone else mentioned it may be possible to setup a direct deduction to a brokerage firm to put it in some sort of index fund or funds. That's at least somewhat higher friction than they money being right in a checking account.
It should not really be needed, as I would get money from the government (enough to live on) if lost my job, and we have universal health-care where I live. But it gives me peace of mind.