Absent-minded! Why? I also wonder why!

These few days including today i am absent-minded!
Today, i forgot to help Tc Liang top-up!
She asked me to do so on 6.30p.m, i promised her before 7.00p.m, she would receive RM30!
Haiz, i forgot, she smsed me and asked where her top-up?
I was asleep!
I immediately picked up my key and rode the bike to nearby top-up center!
Finally, i solved the problem!
Few days back, i was in AC's room, i borrowed dvd from her, my bad habit, like to fight with py, i won. DVD lent to me first, but, i forgot to bring back to my house! Omg! Absent-minded again!
There are lots of absent-minded cases happened on me.
I lazy to elaborate more, i just want find some solution to solve this habit!
Any suggestion?