I remember when I left university I had the same issue — I didn’t know what to do with my day. Actually, it was more that it felt weird to me not to have studying to do or going to lectures. At that time, I was already working so it felt so different and “lighter” not having the studying to do on the side.
I’ll say this though — enjoy it while it lasts. I can now say my life is much more complex than that time. And, sometimes I miss having that ‘boredom’ or feeling of nothing to do. I guess it’s all about the progression of life into adulthood and growing up.