Wanted to be a pilot and rather fancied being a test pilot. Thought that an engineering degree would be useful for that.
However.....................failed the 3rd medical I had with the RAF, (passed the first 2 and also received a Special Flying Award and got a PPL) due to an 'odd' heart (bicuspid aortic valve if you must know!) not detected by first two medicals. After being declared unfit for general duties got offered a university cadetship for engineering branch of RAF but declined on the grounds of; "If you won't let me fly your aeroplanes I sure as hell don't want to fix them just for other people!"
Took the most lucrative post after graduating and ended up in the oil & gas business. It has been pretty good to me over the years allowing me to travel, live in many countries, put my kids through private school and have a reasonable standard of living at no expense to myself.
Not too many regrets......................but would love to have flown fast jets!