A big determinant of what you end up doing with your life is how your prioritize your time.
We're all individuals. We can, with societal, economic, and social limitations, spend it however we like. It is how we choose to spend our time that separates us.
Over the past year, I have become much better at the concept of "compartmentalizing" - basically the ability to juggle multiple things at once.
A problem with working on a few different things all the time is that it is very easy to get distracted, spread yourself too thin, and get nothing done. I wholly believe that it is quite impossible for us humans to multi-task - therefore you cannot operate at 100% if you are worrying about the past, the future - all while juggling the present.
Rather, I try to compartmentalize my day such that I can be present and fully absorbed with what I am doing without having to worry about what is coming next.
If I'm in class, I'm in class.
If I'm at work, I'm working.
If I'm writing, I'm writing.
If I'm at a party, I'm partying.
There is no in between state.
In between states are inefficient. They are less extreme outcomes and, therefore, have less extreme results.
You won't have a ton of fun traveling if you are always thinking about work.
You won't have a ton of enjoyment working if you are always thinking about traveling.
The best thinkers and happiest people I know are able to focus on the now.