Let me try to explain how I think I'm understanding it.... If you calculate that your money won't run out... you are LBYM. Okay. Now I get lost. What does the surplus have to do with it?
Why does it have to be more complicated than that? As I understand it, if the surplus is >=0, you are living below your means, and that's all there is to it.
Hmm.. okay. So, if I'm understanding it correctly if you are on track to FI (as defined - roughly - by "will have enough to support me for the rest of my life when I retire at future date, based on how much I have now and how much I save each year"), you're LYBM?
I think I get it now. Essentially it redefines "LBYM" as "spend less than you make and fund your retirement" (adds that second clause).
This is close to what I was saying.
If you are saving so much that you will have more than enough money to live through retirement, you are living below your means.
If you are saving just enough that you will have just enough to live through retirment, you are living at your means.
If you are not saving enough to live through retirement, you are living above your means.
That was just how I was looking at it; I understand that some people may feel that if you never live off of credit, you are living within your means. But, I do not consider someone saving $100/month, because they are spending the rest, to be living within their means.
All of this is to say, I like the turn of phrase, and I thought it would be interesting to determine the exact level of your means. For instance, I hear of people here living off 25% of their income, I would assume that is absolutely living below your means. So what percentage of your income, in your opinion, would be considered your means?
I know you cannot determine the exact length of retirement, because you can't be sure how long you will live, so it would just be a rule of thumb, not an exact measurement.
I guess for me, I will just start considering a 17% savings rate as being your means.
Also, you guys are fun.