When you have to force yourself to do something. When it is no longer an enjoyable task. Give up.
Giving up isn't throwing up your hands and wallowing in the fact that you can't get something or be something.
Giving up is simply coming to terms with the fact that it is the end goal that you dream about and not the process of getting there that is enjoyable. And when you have to force yourself to do what it takes to get to that end goal, you are always looking at return on investment, on finding shortcuts, and will not go the extra mile to make something happen.
At the end of the day, you get what you give. If you give short shrift to the effort, then that is what you see in the result.
We always know when to give up. We feel like doing so very often. That is the reason we bring on coaches and read literature on how to keep going even when we don't feel like it. We do this because we are in love with the promise that comes with reaching the finish line.
And this is the reason we see so many people fail. For every person that sets out to build a successful startup, only a handful actually do it. For every person that sets out to lose weight, only a small percentage actually do it.
The rest of them give up.
They give up and then rationalise to themselves that what they were after isn't really for them and that they are happy the way they are.
When you are forcing yourself through the process against your will, give up on the idea of the end goal. But find a way to substitute the process with something you enjoy doing.
If you are struggling through your startup, give up. And take on a steady job that gives you the time to pursue side projects that you like doing. If you are struggling with the idea of going to the gym four times a week, give up. And get a dog and take it for a walk or a run every morning.
Give up on your idea of the end goal. If you're enjoying what you do, you'll find a way to get there eventually.