There are many different levels of wildland firefighter from the ones walking in to cut line to the heli-attack and smoke jumpers. So you are asking a question that has many different answers. While I am primarily a structural firefighter that has done some wildland firefighting I will do my best to answer your question. Some of my students have gone on to become wildlands firefighters in places like California, Montana, Wyoming, etc. and when they aren't actively fighting fire they spend their time going out and clearing underbrush from below the trees, cutting fire breaks and conducting controlled burns.
I myself am not a big fan of wildland firefighting now that I am getting old and prefer the structural side of firefighting. However, my students that have gone on to become wildland firefighters really seem to enjoy it.
I hope that answered your question.
Like Mr. Bennett said, your question could be interpreted a number of different ways.
In general, as a wildland firefighter, you will most likely either serve on a handcrew or an engine.
Handcrews, as the name implies, mostly fight fires using hand-tools. In groups of 10-40 people, you will hike to a fire, then begin "digging line" around a fire, in an attempt to remove the fuel from the fire. Basically, if you've dug up all the grass, bushes, and trees in the fire's path, it will have nothing left to burn and will go out. This is very labor intensive, as it involves using various tools, such as shovels and rakes, to dig a ~6 inch deep, 2 foot wide "hole" in the ground that can stretch for literally miles. On this type of team you will also often get to operate chainsaws to cut away larger plants. As Mr. Bennett said, most of these crews drive and then hike to a fire, but some get delivered by helicopter, and some even parachute down from airplanes to remote fires!
Engine crews, as the name implies, work on fire engines. In much smaller groups of 2-5 people, you drive to a fire in a fire engine ranging in size from a pickup truck with 200-300 gallons of water, all the way up to a large engine or water tender like you see in the city, which carry 500-2000 gallons. Once there, you lay hose-lines down, fill water tanks, and sometimes spray the fire directly. Its also common to be placed on structure protection, where you drive through neighborhoods deciding which houses are savable, and then taking actions to protect it from fire before / as the flames are arriving.
There are a few additional specialties, such as driving bulldozers, flying firefighting aircraft, handling incident logistics, etc. but I won't get into those. 90% of wildland firefighters fall into the handcrew or engine crew categories.
Regardless of whether you're on a handcrew or an engine, your typical day is similar.
Before a fire starts, you may start work in the mid to late morning (so that you're on-duty during the late afternoon and early evening when temperatures are hottest, thunderstorms are most active, and the overall chances of a fire starting are highest. You'll probably begin your day with a briefing, to learn about the day's forecast, learn about fires occurring elsewhere, and see what nearby units are available if a fire were to start in your response area. You'll often then workout, which typically consists of hiking or running a few miles (handcrews typically run further than engine crews because their method of firefighting is more physically demanding). The rest of the day is then typically spent performing maintenance on your tools, saws, vehicles, and other equipment to ensure it is ready to go if a fire breaks out. It is also possible that you may go out and do what's called "mitigation work," which involves going out to an area of the forest that is overgrown and "thinning it out" but cutting down some of the trees, and clearing away the brush, and dead trees.
During a fire that's already started, you typically wake up very early - around 4 or 5am, break down your tent / camp, eat breakfast, perform a short maintenance check of your equipment, attend a briefing to learn what the fire did over the previous 24 hours and what the strategy and assignments of the coming 24 hours is. You'll then report to your area and begin your assigned task by 7 or 8am. You will then typically fight fire for about 12 hours, until it's time to set-up camp, eat dinner, and bed down around 10pm. This schedule will repeat for up to 14 days straight, or until the fire is out.
There is some variation to this, especially the schedule, depending where you work. For example, in California they often work 24-hour shifts (24-on, 24-off) for 14-days while assigned to a fire, while many other western states follow a more typical 12-hour shift like I described. Also note that this is just the typical schedule, and some units will have to work a night-shift during an incident to continue to monitor the fire overnight.
If you're considering a career in wildland firefighting, don't factor the schedule into your decision, as it is always changing depending where you work and where you're deployed to. Make your decision based on the values, work environment, and duties you'll be performing. If I can answer any follow-up questions, please don't hesitate to ask!