I can tell you from experience that you may be walking out. It all depends on how deeply buried your wheels are, the soil, your vehicle’s capabilities, and the time of year. Where I live in northern Arizona, each spring after the snow melt occurs, the tow-truck companies have a booming business extricating vehicles that have gotten bogged down in the backcountry. I've seen all manner of rigs, from Hummers to tricked-out Jeeps, get stuck in the mountains here. Preparation before your trip is key.
First, make some calls to the local federal agencies beforehand to check on road conditions. Second, stay on the main roads and scope out any road on foot before turning onto it. Third, if you spend a lot of time driving the backcountry, consider getting a quality winch to use in extricating your truck if it's stuck too deep in the mud.
Lastly, always carry some roadside survival gear like a shovel, sleeping bag, extra food and water, and spare clothes in case you have to weather out a night or two in your rig. If there's no hope of getting the truck out, you may have to call for help or walk out. Towing bills can range from $400-$1200, as charges are a little steeper once the tow truck leaves the pavement