You may, for instance, have a puppy who might still be small enough to fit through your picket fence. You might even embark upon a home improvement project during this puppy stage and decide to have work done on your deck, which would leave small nails and pieces of lumber lying in the grass, attracting said puppy like a tractor beam. In such cases, you may find it easier to walk the dog in the front yard.
If you have begun such a project, you can guess that rainy weather is on the way. If you have a toddler who loves to run (who doesn't?) and who loves puddles (who doesn't?) at home during this reconstruction phase, you can absolutely guarantee that it will rain. You will want to plan ahead and make sure said toddler is dressed early, ready to just slip on rain boots so he can come along to walk the dog.
If however, you have not planned far enough ahead and said toddler is already tiring and approaching naptime, you might start to consider alternative plans. You may assume it would be easier to just leave the child inside, where it is warm and dry. You think about doing something that you know in your heart is wrong. You may be tempted to sit that toddler down at the table with a snack and allow Dora the Explorer to babysit while you run the dog outside for a few minutes. I can't say what works for your family.
Just a word of advice: if you are tempted to attempt such a maneuver, I suggest checking to ensure you have not left a carton of eggs on the kitchen counter before you run outside.