In the West in the twenty-first century, we take bathing for granted. You step into the shower, turn a knob, and hot water appears. There's an apparently unlimited amount, and it's all drinkable, so if you get thirsty during the shower you just open your mouth. (It is hot, not a tall cool drink.)
We have no idea how lucky we are. Until extremely recently, bathing was complicated and time-consuming. Medieval people, like modern people, preferred to be clean and fresh-smelling, but it was a much bigger challenge to get there. One will sometimes hear that "medieval people did not bathe," but this is simply not true. (It's marginally true for the late Middle Ages, see below.)
Think about the effort of bringing water from the fountain or well and heating it up over a wood fire--for which you would have had to lug the wood. The water could have been used instead for drinking or making soup, and the wood could have been used instead for heating or cooking, but you just used it to warm up your bathwater. A big tub of warm water would be shared by multiple bathers. This is no different from the US before the early twentieth century; the Laura Ingalls Wilder books talk about the whole family sharing a tub, taking turns from oldest to youngest.
Medieval people had soap, made from fat and lye, which would indeed get you clean, but it would never be mistaken for a floral-scented "body wash." In monasteries, the Rule the monks followed anticipated a bath Saturday evening, in preparation for Sunday, and for much of the population the weekly bath was the norm. The aristocracy would bathe more frequently if they could.
Hot spring were prized. There are hot springs at Aachen, Charlemagne's capital, producing enough hot water for what we would call a swimming pool. Charlemagne loved to swim and encouraged others to join him in the bath.
The Romans, who had also liked being clean, had built baths across their empire, fed by springs, with fire pits underneath. These baths continued to be used in the Middle Ages. Indeed, most medieval towns had municipal baths, where for a few pennies townspeople could come and get clean, though they would be sharing their water with everybody else.
Medieval bath houses were also commercial centers, where you could meet people for business deals, and buy food or trinkets. They also sometimes were connected to the municipal brothel in the late Middle Ages, which is why there is still a British slang term, "stews," meaning a house of ill-repute (click here for more on medieval brothels).
In the late Middle Ages, after the bath houses were closed out of (justifiable) fear that they would spread the Black Death, aristocrats prided themselves on not bathing. A sponge bath and hand-washing were about the limit. Queen Isabelle (of Ferdinand and Isabelle fame) said proudly that she'd had two baths in her life, when she was born and the day before she married Ferdinand, and that she expected to have a third when she had died and was being laid out. But peasants, getting dirty and sweaty every day, kept right on bathing.