Yeah. Sorta. Definitely. I don't feel like at a certain age there will be no more good things, excitement, freedom or any other positive experiences, rather that it will be too late to start going towards that if you haven't already. To me that age is 30. My family has good aging genes on both sides, but due to a cycle of bad mental and physical health i fear aging into a disabled, dependent and perpetually bitter old man way before I should hit that naturally. I have no friends, no career and no college education, but what i do have is back problems, muscle weakness, depression and a lack of motivation can only make things worse, and this frightens me to no end.
Another factor is the feeling of wasted time. I'm 21, but I already feel like my life should've started earlier. Realistically I can't improve well enough (and that is if everything goes according to my "plan") before age 24 or 25. Every misstep delays it in my mind, no matter how much it really does.
I try to turn my fear into action, but I am prone to panic. I am deathly scared of time, but I can't fight it.