By the time you are 21 years old you have lived half of your life based on your perception

[therandomone]

If you're past the age of 21, you've already lived half of your life. From ages 0 to 21, your brain is constantly changing, and novel new experiences make time feel like it's moving more slowly. As we age and our brains fully develop by around 25, we lose this ability, and time seems to pass more quickly. By this logic, the next 50 years will feel a lot shorter than you think, which is why older people often complain about how short life feels. This realization has made me very happy and able to withstand a lot of life's hardships. I already dislike this dunya, so it's comforting to know that I'm already halfway through.