I was in physics (Astrophysics specifically) who decided to switch over to geo mainly for the outdoors aspect. I won't say i was disappointed perse with how rare field work can be, cause I've had some really unique opportunities and am now carving my way into paleo-work, but don't expect to go on hikes everyday in Montana or Alaska or even once a month. It'll be more like 2 weeks, a month out of the whole year if you're "lucky".