I currently easily live off of around 44k a year pretax, while contributing around 8k to my 403b and setting aside at least 3k a year for vacations. Can't see why being a physician will suddenly make living off 2-3 times as much seem impossible. Don't live in an expensive city, don't send your kid to private school, don't buy a McMansion, don't get a luxury car, and don't buy **** you don't need. If you don't buy into the myth that acquiring stuff will make you happy and don't fall victim to lifestyle inflation, you will likely be not only much wealthier but much happier overall.
The amount you need to retire is -very- dependent upon what your spending level is. You can retire forever on 25 times your planned withdrawal rate, assuming a 4% drawdown on investments that are expected to return 7-8% (yielding 3-4% interest to adjust for inflation). If you keep your spending down to 50k pretax, you're looking at $1,250,000 to quit forever, $2,500,000 for a 100k income, or a whopping $5,000,000 to retire if you expect a 200k income (your nest eggs could actually be substantially smaller for each bracket, but I really don't feel like doing the math to compensate for capital gains tax vs regular income tax right now).
If you live like you are middle class rather than upper-middle class, get a Camry instead of a 7-series, play basketball instead of golfing at the country club, etc, you can put away the money you'd otherwise be blowing on luxury expenses. The average middle class family lives off of a household income of just over 51k a year. At 100k, you are earning nearly double that with your income alone. I dare therefore say that it is perfectly reasonable to survive this salary without a great deal of hardship. Given the downward trajectory of physician salaries, I do not think making 100k a year to start is a great idea. You would be much better off working full time and socking away a nest egg while the getting's good and time is on your side. If you keep those spending levels low and work a bit of overtime, you might even be able to enter partial retirement early while pulling 100k a year for not working at all.