Every time you get into it, hoping that it will start. And not just when it's been sat outside your house for a while. When you stop for petrol (gas), or in the car park after buying food, sitting behind the wheel and hoping it starts again. The restrictions that get placed on you when you just can't rely on the car always starting.
For your life, a mostly-starts car is in theory better than no car, but for mental health it's corrosive. Every plan you make carries the rider "unless the car doesn't start" and you end up restricting where you drive to places that, if you were suddenly carless, you could still get home from. Any time you're outside the safety zone, there is the constant fear "what if it doesn't start?" Being afraid, having that stress, all the time is just mentally corrosive.
If a better job comes up and it's not near public transport, every day is a gamble on being able to get to work, and get home again. Spending your evening worrying about whether you'll be able to get to work in the morning is a horrible way to live; perpetually unable to relax. At least once I simply sold it for scrap and gave up entirely on doing anything that needed a car. Such a relief, but I was in the privileged position of being able to live and work without one.