I have run 99% of the days for the last 47 years. I find my interest in running began to wax and wane after about I reached ~45 years old.
There were lots of days when I did not want to go out the door and run, but I still went out there and ran anyway. Sometimes it was just out of habit.
I can not remember a single day when I regretted going out for a run, after the run.
There are hundreds of reasons to run. If you are only running for competitive reasons you will find it difficult to motivate yourself when you start to slow down and become less competitive.
Its ok not to run, and there are lots of other activities you can do which provide similar physical, mental, & spiritual benefits. But running provides one of the easiest, simplest and most adaptable ways to obtain those benefits.
With a busy life it can be valuable to schedule runs, as otherwise they may not occur at all. So if every run is a chore right now I believe your plan to schedule 3 runs a week is good. You might try scheduling time for 4 runs a week, and then trying to fit in other runs or other activities when you can.
If you do not schedule anything, you run the risk of getting so far away from a basic level of fitness that you could start slipping down the path of becoming sedentary, fat and worse.