day by day, that's how I do it. Some days are better than others. As long as the kiddos are fed, clean and rested, I'm good.
I think when you pause to ask yourself "am I doing a good job? is there something I can do better?" That is when you're on the right track.
There will always be some measure of mom guilt. It's just the nature of motherhood. I make mistakes but I learn from them. That's all I can ask of myself. Be able to give myself grace and compassion for doing this very job is necessary.
I also think it's important to take a little time everyday to do something that is outside of motherhood. I knit or play video games. Being able to forget that I'm a mom has been helpful for mental rest.