Afraid for Uncertainty

I read "La Tahzan" which mean dont be sad a few days ago. There is a sentence that still stick in my head until today, and I keep going repeat this sentence again and again. It said, do not be afraid for future that uncontrollabe, just keep doing the best for today. I really love this phrase, easy to read but I am not sure that I am fully understand and agree what this author said.

Of course I am afraid for something in the future that I can't control, I am afraid that what I have been done so far its enough to give me a peace life in the future. I am afraid that I will not have any income in the future and should depend on someone, even this someone is my own husband... I am afraid...and yes I am really afraid.

I am afraid that I cannot give the best for my son, I am afraid that my son will not love me anymore when finally he meet with the girl that he loves so much, I am afraid that my parents will leave me alone in this ugly world... I am afraid...I am so afraid.

When this feeling hit my head, and give me a stress of thinking this kind of uncertainty, I am back to the book...and trying hard, and thinking what I should do today...just do the best thing I can, and leave all this worried things behind me...

I can't answer that...but just do it...and follow my heart ...