Can somebody help me in improving this sentence, please? Let me know even if it doesn't need any improvement.

I came to know my weaker subject areas and started working on them.

And this one too. Any commas in between or a better sentence structure?

Also, spending one year waiting for “my moment” has taught me patience and has given me a certain tenacity that I will carry forward into other areas of my life.

My essay, actually, is about a decision taken by me. I've failed an exam once and I am waiting another year to attempt it. "my moment" in the above sentence is the moment of my success this time.

The first sentence is fine just as it is. A suggestion for the second is that starting the second sentence with "also" can be a bit of a weak transition from the previouse sentence. It all depends what the "also" is referrring to. Depending on what the previous sentence is, this sentence may be improved with a slight rearrangement:

"Spending one year waiting for “my moment” also has taught me patience and has given me a certain tenacity that I will carry forward into other areas of my life."

As for the phrase "certain tenacity" - what do you mean by "certain?" I assume you mean that you are more tenacious now than before - perhaps "has given me a measure of tenacity... " or "has given me patience and increased tenacity.. "

Thank you for your help ebaines. You are right about the second sentence. I will surely check my mistakes.

That was really helpful. Thank you ebaines. And yeah, you were right about the "certain tenacity" and I will correct it.