I especially admire those who possess self-discipline. I marvel at the magical things they can accomplish that I wish I myself could do. In the past, I have tried and tried but failed. Now, a new thought comes to mind: I will break down my aims into more modest goals. For instance, if my aim is to avoid fruitless scrolling through Facebook or Youtube for an entire year, I will put aside that daunting goal and settle instead for just one single day. If even just one single day without these things still proves a struggle for me, I will settle for a mere five minutes minutes of scrolling and try gradually to observe that rule for longer: one week, then two weeks. Let's give it a go! My hopes will lead the way. When you say "I admire somebody who..." it sounds like you have one particular person in mind. If you mean to talk about people in general, "somebody" is the wrong word. It makes good sense to use the simple past in your sentence that starts with "In the past..." However, I still prefer Present Perfect ("I have tried") to emphasize your experience rather than events that occurred. The Present Perfect works perfectly to discuss experiences. The word "now" deserves to be followed by present tense. I gave up FB years ago. That decision improved my life greatly.