Go Heavy
Today lift or carry something heavy. What does heavy mean? It means something you can lift only for a few reps or carry for a short duration. Of course there are the usual disclaimers here, be safe and sensible. This isn't a competition.
If you're a gym bunny it could be a barbell, dumbells or kettlebells. If you train at home or outdoors improvise with a backpack filled with stones, a sandbag, a large rock, tree trunks or a duffel bag filled with lead shot.
If all else fails grab one of your kids or training partner and perform an exercise bearing their weight - such as a squat. Be adventurous and enjoy.
Progressive overload is what's important here. In order to get stronger you have to continually challenge the body with progressively heavier loads. In Greek Mythology, Milo of Croton became the strongest man in Greece by lifting a calf on his back every day until it grew into a full grown bull.
Use Milo as your inspiration.