Not conquering the Philistines

Joshua 13:1 Now Joshua was old and well advanced in years. Yahweh said to him, “You are old and advanced in years, and there remains yet very much land to be possessed. 13:2a “This is the land that still remains: all the regions of the Philistines … (World English Bible, public domain.)

From my daily Bible reading plan for today. 

I guess I'd seen this before, but don't remember it. Joshua and the Israelites were supposed to have conquered other nations, including the Philistines, but they didn't defeat them all. The Philistines were a nuisance to them for quite a while afterward -- think Goliath, as one example, and Delilah as another -- because they hadn't wiped them out, as they should have. Goliath was in the time of David and Saul. By this time, the Israelites had gone through several judges, and had been conquered more than once by other nations, until, each time, they repented of their idolatrous ways.

What have I not conquered, with God's help, that I should have, which is giving me problems?

Thanks for reading.