Labrador Retrievers can become lazy if they are not encouraged to exercise.
Compound this problem with over-feeding, which is very common, and extra pounds
are easily put on. Taking them off again is harder work, requiring a more
appropriate diet and an effort to increase vigorous exercise time (gradually, of
course, to prevent possible muscle injury or overexertion).

Swimming and retrieving games are natural outlets for Labrador Retrievers.
These activities are ones that the breed excels at and enjoys, and they give a
complete, full-muscle workout that tones the entire body. Having access to a
swimming area may be a problem for most owners, but retrieving games can be
played anywhere.

Labradors have great stamina, but owners must use common sense. During the
summer months, limit strenuous exercise during the hottest part of the day and
provide an ample supply of fresh water. In the winter, a Labrador in good trim
should be able to withstand the cold very effectively and should not be kept
housebound. If the dog is out in the rain or snow for any length of time, he
should be dried off when he returns to the heated
indoors.