This entry is really great overall! My comments below are about very high-level details. :)

The Shortage of Writing Time

I haven't written any notebooks for one week. [Either "I haven't written in my notebook for one week" or "I haven't written any notebook entries for one week" is better.] That's so bad. The problem is that I have recently been busy with my work. When I feel free is the time for me to hit the hay. ["When I have free time, I would rather hit the hay"--is this what you mean?]

During this week, various topics and stories inspired me. I imagine that if I had had free time, many memoirs of mine would have been posted here. Being lazy is another reason for lessening of notebooks my writing fewer notebook entries lately.

Motivating Staying motivated to study English by myself is a must for me if I want to improve my English ability. Thereby, I have to come at a price so that I don't fall short of my goal. [I'm not sure what you mean by "have to come at a price." Usually we use that phrase to say something like "I can get in shape, but it will come at a price--I'll have to start waking up extra early so I can exercise before work."]