I find working towards wins (new users or customers) helps to replenish my excitement and enthusiasm for my project, so I aim for those.
Otherwise, I just end up grinding until my mind eventually says enough and I'll just have to stop for a few days. I've considered whether a more balanced schedule could help but have currently settled on the opinion that while we may be looking for the right approach, there isn't one, only trade-offs. You either neglect progress on your project or neglect your personal life. You just have to decide how important each of those are in your life, then prioritise accordingly and accept the trade-offs.
Otherwise, I just end up grinding until my mind eventually says enough and I'll just have to stop for a few days. I've considered whether a more balanced schedule could help but have currently settled on the opinion that while we may be looking for the right approach, there isn't one, only trade-offs. You either neglect progress on your project or neglect your personal life. You just have to decide how important each of those are in your life, then prioritise accordingly and accept the trade-offs.