How you spend your time is vital to your success and overall happiness in life.
Learning to say "no" to people and activities that don't support your overall goals and life plan is one of the most valuable skills you can develop.
Quantum physics aside, you cannot be in two places at the same time so you must be vigilant in planning your days and deciding how and where you spend your time.
It's been said that time is the only thing we can never truly replace.
You can lose money and replace it. You can lose friends and replace them. Material things can be replaced. But not time.
You can never get time back once you've spent it.
Use your time wisely and learn to say no to things that are not time well spent.