I need to get out, I booked a flight to Europe and am ordering gear from REI. I'm going to walk the Camino Frances starting in two weeks, but I need advice. I am a big boy with bad knees, 300lbs.

I currently don't move, I get winded going up stairs and brace myself to sit down. I'll start out by going slow but how bad of an idea is this? It's just walking right? I hear it's an easy one to start with. I can do this right? Besides toe socks is there anything I'm forgetting to bring? If I don't do this I fear my life is over. I'm giving myself two months to finish it.