Writing great blog or having pet project after working full time is equivalent of working overtime or crunch. Had this been effective, persistent overtime would be effective too.
Which is why it is not happening. The actual rest time and hobby is when you do it whenever you feel like and stop how you feel like. Once you make it project and treat it seriously, it is work.
Also, other stuff that is done after work: cooking, cleaning, shopping, picking up kids and talking with them, sport to be healthy. These amount to not exactly small chunk of time.
Which is why it is not happening. The actual rest time and hobby is when you do it whenever you feel like and stop how you feel like. Once you make it project and treat it seriously, it is work.
Also, other stuff that is done after work: cooking, cleaning, shopping, picking up kids and talking with them, sport to be healthy. These amount to not exactly small chunk of time.