How do you solve the problem of being gravly serious all the time while home schooling.

I have a large family and am homeschooling half of my school children at the moment, I find it almost impossible to have light-hearted times with the children. I think it would help but, I am always so concerned with the behavior's that are always popping up their ugly heads. I correct and teach the right way, trying to impress on the child/children how important things are etc. I have very high spiritual and social expectations of my children and it burdens me greatly to see them often so out of order. The effect being that I find it hard to lighten up and break out of serious mode. My colour code showed me as just under half blue, over 1/4 yellow, less than 1/4 red and a tiny slither of white. When in the past, I was at work I could often have happy and joyful times with my co-workers and those whom I managed in the job, to the point where reports came to me that co-workers enjoyed my company and missed me when I couldn't be there. But I have always found it hard to be this way with my children, the awesome responsibility grips me and drives me. Do you have any tips for how lighten up at times and to bring more joy into the home and help with building relationships. I long for some way to not always see the problems, but to just have some joy and fun with the kids. Even when we do family activity night or I stop and play a game with the kids, I find it so hard to detach from the burdens and worry's, all the work that needs to be done and just relax. Sometimes the activity is great and other times we end up with so much bad behavior, it spoils it. Some of my older ones almost mock or at least look at me like "that's not even funny" when I try desperately to make a joke etc. and I think it's because it's not what they are used to, coming from their parents. I think I need to create more joyful moments with the home schooling to but find it very hard to do this while trying to meet all the different age levels of need, baby, preschoolers, primary and secondary. Any ideas would be much appreciated.