Clean up the yard.
Seriously. If I take 10 minutes & put all the outdoor toys away where they belong - sandbox stuff in the sandbox, balls in the bin, construction toys on their shelves & park the bike & red car in their places, when the boys come home from school, they immediately want to play outside. It doesn't matter if it is warm, cold, raining or a driving hailstorm; they simply *must* play outside. They've barely looked out a window for the 2 previous days when there were balls, loaders & buckets strewn across the lawn. But now that their stuff is put away, they must go out & put it back. Perhaps they are marking their territory? That would make sense, if we had neighbors. But the cows really don't care & there is a barbed wire fence to keep them out even if they did care..
The boys have shown real improvement about picking up in the house. They seem to now understand that the blocks have to be put away before the train tracks come out and the trains need to be back in their bins before the pirate fleet sets sail across the floor. Most of the time they will respond positively to a reminder to put away the toys not being used. Sometimes they even do it unprompted & then come and find me to show off "Wook Mama! All toys away!!"
Outside lacks this progress. Winter is probably not the best time for frequent reminders. It's cold, windy & rainy and I am not inclined to stand out there insisting they put things away before they come inside. Warmer weather is coming though and I think it is time I started reminding them the outside toys must be put away as well.