I try not to use too many mods to preserve the vanilla Skyrim feel. Familiarity is key. However, I do want to add a little realism. So here are the mods, until they break:
FrostFall – This mod adds hypothermia and a body temperature system. Blizzards in the mountains can kill me in minutes. If I go swimming, I have to dry off by a fire. I have to wear warm clothing if for some reason Billy decides to go exploring in the arctic tundra. If I’m not careful, the rain will also chill me to the bone. I can also create campfires and tents. It’s a very well-designed mod, surprisingly deep and integrated well with the main game’s mechanics.
Drink Eat Sleep Bathe – Self explanatory. To prevent weakness I must eat properly, drink properly, sleep properly and bathe properly. You can imagine what the first three involve, but as for the fourth, McGonian’s stench will put off the mild-mannered nords of Skyrim unless he keeps a supply of charcoal and takes a dip in a river every once in a while.
Showers in Inns – Self-explanatory. If I’m in Winterhold and smell weird, because of Frostfall I can’t bathe in a frozen river. That’s where this mod comes in!