I'm not sure whether this is a phobia or just an irrational fear, but I'm afraid of growing old. I'm 21, and I already have this kind of fear, it doesn't make sense at all. I'm not worrying about wrinkles or saggy skins, but I'm worrying about "I'm already really close to 30, and I won't be able to do many things as an 'old' people. I can't walk fast. How about my health condition? And etc.". At this point in my life, I feel like I only have a little time left, time is ticking fast, and I'm racing against time.