You have probably heard some people talk about wool as "self-cleaning". That is because the fat from the hair sacks of the sheep work as a type of coating. That makes dirt and smells not stick as well to the fibers. Lanolin also has bacteria-killing capabliities, and helps remove bad smells. This is usually only found in untreated, organic wool.
Unfortunately, lanolin disappears with time, also in untreated wool. But there are solutions. You can give your wool garment a wool treatment to freshen up the amount of lanolin. This is how you do it:
A wool treatment is easy to do. Mix lanolin in water and let the garment lie in the solution for a few hours or overnight. The specific amount and instructions depend on the wool treatment. Usually, the lanolin will stay in the garment for multiple weeks, depending on use and wash.