To answer the original question - my motivation is time - the goal of spending it doing what I want to do with it - with my family, and pursuing my interests.
About controlling spending when going straight from college to a 6 figure income. Well, I'd say some controlled splurging is probably in order to reward yourself for making it through 7 years of college, and in a very challenging degree. BUT...there is a deadly trap you have to avoid. The splurging phase can rapidly turn into the longer term financial commitment phase. You have the 6 figure salary, but you now also have the payment on the 450,000 house, the 80,000 car, a ton of credit card debt to make payments on, and so on and so forth. Suddenly, despite the great salary, you can find yourself living month to month. Now, you must continue to make the great salary, just to get by.
So, with that sobering thought out of the way, the best way to avoid that is to just think through how much the thing you are thinking about buying is really going to cost, and compare that to how much enjoyment you expect to get out of it.
Ok, an example... Being a bit of a car guy myself, a couple of years ago I was starting to get lustful thoughts about a corvette. Between bouts of uncontrollable drooling, here's how I thought about it, and eventually this made me decide not to get it. To figure out the cost, I took the cost of the vette and subtracted the cost of a reasonably nice normal car, say an impala. The reason for this math was that I wanted to separate the cost of the need for a car, from the cost of the emotional desire to get the corvette. So, about a 30k difference, maybe a little more. Then I figured I'd spend about another 12k in finance charges over 5 years, about 7k of that attributable to the "desire" portion of the cost. So, 37k now for the desire part. Then I figured with retirement at least 15 yrs away, over that period, that 37k could grow to 75k quite easily if invested in something other than a corvette.
Then I tried to figure out how much enjoyment I'd get from the real cost of 75k or so. I knew that for the first month, every time I saw it in the drive I'd be like "Oooooo", but after that the "Oooo"'s would only come ever 2 or 3 days, then only occasionally, and eventually it would just be another set of wheels to me. In the end, I figured I'd probably be paying about a grand for every time I said "Ooooo". Not worth it.
All of that said, I do splurge now and again, but I make sure it's on stuff I'll get lasting enjoyment from. I love playing guitar, and have spent about 2000.00 on my amp, and another 1000.00 on my main guitar. A fair bit of change for a hobby, but I get hundreds of hours of enjoyment out of that every year, so to me, those kinds of things are worth spending a bit on.
Off topic - I noticed that in the other thread about your parents that you are from the DFW area. Me too. Work in Dallas, live up in Allen.