Find a job or chore that is normally done with a tool. Look for something that is not impossible but much harder without the tool. For example, washing dishes with a dishwasher, driving nails into a board with a hammer, brushing teeth with a toothbrush, or cutting paper with scissors.
Instruct your children to get the job done without the tool. As they work (and probably complain about how hard it is), encourage them to keep going and try to do it no matter how hard it seems. At some point (maybe just before they get overwhelmed) allow them to use the tool to finish the job.
Discuss how the tool made it so much easier to do—even to the point of not making it a chore at all. Compare how our life can be hard if we don’t trust in, hope in, and use the strength that God provides. His strength will help us run through life and not grow tired. We will see this strength when we hope in Him.