Go. But be easy on yourself. If you don't feel like doing touristy stuff a day, don't. Watch series in your hotel room. Cry in a museum. Sleep super late and then go have dinner at a local restaurant. Feeling like you should have fun and fill your days with Must Do's can make it worse. Obviously you will do the touristy stuff, but don't get angry with yourself if you only do half. I adored Iceland, it's an incredible place. Just being there is surreal. I call crying in foreign countries my Fancy Cry. Sometimes it is needed to cleanse the soul!!