That's a pretty big question, with a couple of different interpretations. If you are asking how I handle thinking about the passage of time, the easiest answer is to make it tomorrow's problem. This is probably not the healthiest answer; but it doesn't pay to stress over inevitabilities, so I just do my best to put them out of my mind.

If you are asking the best way to utilize your time, my recommendation is to start focusing on yourself immediately. It's very easy to prioritize work by staying late or overworking yourself to make your bosses happy, but no amount of overwork will ever satiate your company; it will only serve to drain the life from your body. It's very important to set firm boundaries with your job. I, personally, will not even look at my work phone or computer the minute I leave the office (on Mon-WFH days) and have a hard stop every day at 5PM unless agreed upon well in advance. You lose so much time and energy to your job that just standing firm on your boundaries can be a huge QoL boost.

Please also do your best to cultivate a creative outlet as a hobby. A lot of people don't think they are/can be creative, but anyone can be creative if they find the right outlet. It could be art, sewing, crochet, music, writing, or even creative programming. The important thing is to find a way to explore your feelings and do something productive with them. In my experience, I am often the most vivacious are when I am making art in one form or another; I highly recommend it.