I can relate. I paid off my house early (a 15 year note). It is a nice house, 4000 sq feet, likely appraised at $1M (I didn't pay this amount for the house).
It is a great feeling for about two months, and then you realize: 1) you should live like you lived before, except that the money you save now needs to go for savings and investment, and 2) you really need to get smart about investment, never forgetting that there is a relationship between risk and return. There is a temptation to slide into riskier investments because you think you have lots of money. There is also a temptation to spend needlessly. Although I don't agree with his politics or religion, I listened to Dave Ramsey podcasts just to remind me of the importance of saving and minimizing materialism (this is not a discussion or an endorsement of Dave Ramsey, just a reminder that thinking about being thrifty in any way is helpful).
As to investment, especially at your age, there is a tendency to want fast and big returns, because that is essentially what you feel you just did in paying off your mortgage early. But you really need to patient and be there for the long haul (I traded futures to pay for professional school, so I am not risk averse). The truth is that most of us have some insecurity and there really never in our minds enough to retire unless you get in the class of the truly very wealthy. So while paying off the house is great, some of the same challenges exist.
Good luck in your travels, and look for value when sending your kids to college (something I did not do as both went Ivy League).