Is having a little lump in a woman's breast a serious matter?

I just wanna ask this out. I found 27th of last month that I have this little lump in my breast and up to now it's still here. I don't wanna react too much but sometimes I just can't help but worry. Enlighten my mind

It is wise not to overreact but it is very foolish to ignore it. You should see a doctor to determine what it is as soon as possible.