Things that stimulate and engage still occur and can be discovered, of course, but they are less frequent. It's like the saying that was so popular at the end of last century: BTDT. (I can't bring myself to typing out the actual words - it's not a phrase I never used or liked. It certainly did not excite me. Not like some phrases, such as the 70's classic - 'Keep on Truckin' often accompanied by the wonderful Robert Crumb illustration.)
Whatchu talkin' about, Willis?!
I guess I'm saying to anybody young - enjoy getting excited about stuff - and doing new and heart fluttering things. Life is stimulating in other ways as you age - but it is never as eye-poppingly vibrant as it is in the first few semesters.