When my kids were young, my wife was a stay-at-home mom and a home schooler. She found many things to keep everything fun and interesting.
Here are a few:
Go to the library! Libraries have a wealth of things for kids! Many libraries have whole sections just for children and offer special programs and activities for kids.
Go to the museum! If you live in/near a large city, there will be museums. The larger the city, the larger the museum.
Without leaving home, there are things you can do too. Kids love to help with anything you are doing. If you are painting a room, let them help! If you are cooking, pretend you don't know how to do it either and go back to the recipe book - show them how, if they know how to read and follow directions, they can make anything!
Find out what your kids are interested in. If they like airplanes - make balsa wood planes. We made kites. We started at the library, and selected books on kite making. Then we read the books. The we went to the craft store. We got silk, dowels, and even a little hand-held battery powered sewing machine they could use. We colored the white silk fabric with colorful markers... It was fun! (And yes, they flew!)
"Staying Entertained" is part of the problem many parents have. It is not your job to entertain your kids. They have a very short attention span anyway. It is best to develop routines to fill the day, and having set times for activities keeps the day interesting for them. They may not like 'clean-up time' but soon it may be time to feed the pets, or go to the store, go for a walk, go to the park, study math, reading, lunch... you get the idea. Give them a watch so they can proudly say: "It's time for lunch!" Of course you have to be flexible, and always allow for surprises, like a trip to the beach, or some other activity.
Soon they will have jobs and school activities and friends... Your full-time parent job changes to a part-time job! Then later, you graduate to a consultant. You will always be a parent, but it takes less time as they get older. I love seeing my parents having fun with MY kids and I see my future... I get to do all these things over again with grand kids, but just here-and-there, not every day.
One last tip: Try and say "yes" as often as possible. I heard this somewhere along the way. It has helped. If at all possible, I say yes. Kids have great ideas and suggestions, if you listen. Sometimes I ask them what they think about something, or what THEY would like to do. You will get to try lots of new things! You may not like pancakes with made with chocolate cake mix and chocolate syrup and chocolate chips - but they will never forget that you made them together! (and they were actually delicious!)