I've been thinking about this very thing, only in terms of trying to decide if I should just start pouring money into my mortgage and stop saving as much for retirement. With the small extra payments we are making into the mortgage right now, it should be payed off in about 15 years. I am 34 with $300,000 in retirement savings. Running the numbers different ways, it seems like I'm at about equilibrium where if I don't add another dime to my savings, assuming a 7% ROT, I should have enough to retire about when I pay off my mortgage... assuming 5%, then 5 years after I pay off the mortgage. I keep running different scenarios trying to decide on how to rebalance my savings/pay down rate, or trying to decide if I should just stop all savings and drastically cut back on work instead, entering semi retirement now :) Either way, I am celebrating the same victory, being at a point where I could scale back to a subsistence wage and still have a comfortable retirement at a "normal" retirement age, likelier much earlier. It is pretty damn exciting! Congrats.