If you've been thinking of making a personal blog or you currently own a personal blog I can't say that it's not good but you can call it more of as a diary instead. Specially if what you are posting are about what you have been doing in a day. This is because you will not get visitors to your blog. Unless you are well known celebrity or politician you might actually get people to visit and read about your blog.
And when it comes to monetizing your blog which i'm sure is the main reason why a lot of people are blogging there is a very small earning potential for a personal blog. As we should all know how much you earn will depend on the amount of visitors of your blog so if you can't make at least 100 unique visitors for your blog a day. You can never expect also to earn money.
I'm not saying here that you can't make or a personal blog is useless, my point is there are many other topics that you can choose from. And those topics can also give you opportunity to earn big money with an informative and well made blog. If you have a personal blog right now you can still continue writing on it but i advice you to make a blog that kind of something that people can get lot of information and entertainment.