Sideprojects Are Hard
vinoth.net
vinoth.net
Side projects are definitely hard. You have to optimize and focus on all the right things to have any degree of success.
I would also think about the worst case scenario and best case for anything you do. Worst case, always make sure you learn a lot of lessons and skills. That way your time didn't go to waste if your project fails.
As you stated, you also have to care more about your side projects than other things (such as free time, being free of stress, or performing super well at your dayjob). There are a lot of sacrifices involved.