I decide to study harder

I have been always interested in many things, like literature, music and design, but I haven't made it yet because I only did half of these things . I hated that I couldn't concentrate on what I was doing. But I must try now, and I don't want to waste any time. I have come up with a rule: do one thing at a time and finish that thing. Come on.

I Have Decided to Study Harder

I have always been interested in learning many things, such as literature, music and design. However, I have not succeeded at any of them yet because I have only put in half the effort. I hate that I couldn't concentrate on what I was doing. Because of this, I feel that now I need to study harder. I don't want to waste any time. I set up a rule: I will now do one thing at a time and always finish that thing before I move on to the next one. Come on. (Perhaps you mean "I can do this")

Great job! There are a lot of complex ideas within this and you did an excellent job of making your meaning clear. I changed a bit of grammar and punctuation errors and rephrased a few ideas. I wasn't sure what you meant by the last sentence. I suggest "I can do this," if your "come on" was entended to be self-motivating/encouraging. Wishing you all the best in your continued studies!