It's the human mind's way of grasping and understanding change. T his idea that time doesn't exist may sound rather radical, especially if you're used to thinking in terms of relativity or time as a dimension. But this is an old definition of time, which is still held today by many philosophers, especially among Thomistic philosophers. T here is some practical value to this understanding of time. The changes going on around you, even within yourself, as still happening at the same speed, but time , the mind's perception of changes, can go faster or slower.
Time is a concept developed by the human mind.
W hat you find is that time goes faster for a child than it does for an adult. Then, it makes perfect sense that a child's attention span seems shorter than an adult's. It's just that time is going by faster for a child than it is for an adult. I was a child, it took forever for Christmas to come. The older I get, the quicker each successive Christmas comes.