All I could encourage you to do is keep focus on what you want to do or have to get done. Sometimes when we are stuck in the everyday routine, we lose hope and feel like everything around us is crashing, then one thing mounts on top of each other and it becomes overwhelming.
Take a trip to your mother for a day or so with the kids for a change of scenery.
Be a friend to someone new in the grocery store and visit or talk with them sometimes
Make lunch for your husband and take a drive to his workplace or at a park and have lunch together
Remind yourself why you are where you are, set a goal and keep your eye on that. When we see an "end", we won't get so burdened by the journey to get there.
Select a specific room for your kids to play and enforce that they only play there so that when someone comes to view the house, the toys are not all over the place and you can quickly get that one room cleaned.
Instead of taking a walk for the exercise, try creating a game to play with your active age kids and dance to music with them, jump around etc. Walking is nice but it can be boring too, especially if you don't have much to do in your area.
We are not in your situation and can see more clearly, but hopefully you get other good suggestions to uplift your spirit.