Sometimes the important thing is that you keep at it
There are things you do that are easier on some days than others. On those days when it is harder, it is important to keep at it. Trying may be all you do some days, and it is enough. Some things take more than one person working for more than one lifetime to get to the completion point. It is important to understand that some things are going to take longer than others to get done, but that does not mean that you should do only what can get done right now. Sometimes the important thing is that you keep at it, not that you finish it.