Most of the time I ruminate on things I don't have or on failed plans, but for now on I want to be thankful for the good things I have in my life and for the small things I have accomplished.

It is a close thing, but "the" sounds a bit more natural to me here.

I don'tly have so manythe one friends, but I have one who is worth than many of themthey are worth as much as many.

I really like the contrast quality/quantity in this sentence; but it is hard to say it in the way you're trying to. An alternative might be: "I don't have many friends, but it is the quality, not the quantity, that counts."

And a family, though is crazy someat times, iswho are always supportive.

I'm happy for being able to write this entry in English by myself and for being able to reading English news on the internet easily, and watching some videos without subtitles.

I think theses things are great accomplishments.

Most of the timeUsually, I ruminate onver things I don't have or on failed plans, but forom now on, I want to be thankful forof the good things I have in my life and forthe small things I have accomplished.

I would personally write this like so: "I usually ruminate over things I don't have or on failed plans. From now on, though, I want to change. I will try my best to focus on and be thankful of the good things that I have in life as well as the small things that I have accomplished."

I'm grateful for having a roof over my head, and healthy food everyday, for being physically healthy and having a stable job.

I don't have so many friends but I have one who is worth than many of theme same as (some large number, say 100).

And aI'm also indebted to my family who, though is crazy someat times, isare always supportive.

I'm happy for being able to write this entry in English by myself and, for being able to reading English news on the internet easily, watchingand even understand some videos without subtitles.

I think theses thingsThese are all great accomplishments that I am proud of.