God our creator made and gave us cells for one reason only: to get the job done. Cells do so much, we have skin cells protecting the body and gland cells that aid the body, nerve cells that carry electrical impulses plus in addition to that we even have our very own chemical factory in the liver and the cells that work there!
But there is one thing that all cells must do that is more important than all others: staying alive! To stay alive and in good shape they need food for a constant struggle to keep everything functioning and working smoothly; many a times that includes getting rid of old dying cells and replacing them with new ones and then keeping the new ones clean.
There is a Bible verse where the author says that he will praise the Lord because he is fearfully and wonderfully made...that guy had the right idea! First, he realized something very important, God had wonderfully and greatly made him; his body was everything God intended it to be and then the author did the right thing: he praised the Lord for it!
There are many things that cells must do to keep alive, one of these things is maintaining the proper osmotic pressure; water is always moving in and out of our cells, if the cell does not take care it could either burst from too much or shrivel up and die that way. A constant battle!
One other thing that cells have to do is keep the proper amount of pH in balance, all cells need a certain amount of pH or chemicals and acids to keep them going; by using their ion pumps, the cells are able to maintain a balance and in so doing they keep themselves and us alive.
Some other daily activities performed by our cells is keeping the food and waste going in the proper direction; every cells needs nourishment, without it they would all die. And of course there is the maintenance and repair that goes on literally all the time to keep us and our bodies in top order so that we can have that tremendous gift called life.