A Power of Attorney has two types: general and enduring. General Powers of Attorney lapse automatically if the person granting the Attorney loses capacity. ‘Enduring’ means that the power continues, even if the grantor of the Attorney loses the capacity to make decisions.
Although contemplating your future about your potential incapacity to make decisions is far from pleasant, it is very important. For example, you could be overseas and cannot sign a document because you unexpectantly are mentally capable of making decisions. Or you could become ill and not have the capacity to make decisions about your healthcare treatment.
Appointing someone you trust to be Power of Attorney for you, to make decisions on your behalf gives you the choice. You choose who will be that person making the decisions in case you are unable to make decisions about matters that concern you. You can appoint more than one Attorney who can act jointly (together), as a majority (two-thirds, etc) or severally.