From what I’ve read, the key to appreciating time as it passes is having new experiences. Routine and repetition reduces the number of new memories and novel neuronal connections that are formed. Time seems to pass in large swathes.
When you are young, every day brings a previously unmet concept or activity that requires understanding, development and adaptation. These act as buoys in the sea of routine, offering perspective on the passage of time. As such, time seems to pass more slowly.
My five year old daughter always references specific episodes to understand when something happened in her life. These reference points are significant moments for her, but may be routine events for some experienced at life.
The key to feeling like your life isn’t disappearing from underneath you is to have a novel experience everyday - gain a skill, engage your brain wrestling with a complex concept, travel, be challenged, make yourself nervous, fight against mediocrity and routine….
Or you could just work the same job for 40 years, watch TV every night and holiday in the same resort each year. I’ll meet you when we are 80, but I’m taking the long way around.