Hi D.,
I was the same way. I am not really a rough and tumble kind of gal, so finding outdoor activities I could enjoy with my son was a challenge. I found that our most favorite activities included walking. I would think of things to look for outside like pinecones or rocks or whatever, then when we finished, I would let him bring the items in the house and make something with them. Also, I was very busy when my first son was young, working part time and going to school full time, so I found ways to include him in what I was doing. Trust me, it will work.
I would bring him in the kitchen with me while I cooked and give him things to do...for instance, "get mommy the green measuring spoons". He won't know what they are, so you give him verbal directions on how to find them. "Go in the drawer where we keep the forks and look for the green plastic spoons...Oh, here they are, see they have numbers on them". It keeps him busy, gives you a chance to cook and spend time with him and also gives you tons and tons of teaching opportunities. As a single parent, you know the importance of being independent. If you teach him at a young age how to look for things and help it will help you and him in the future. Having him search and think will develop wonderful problem solving skills.
My son is 11 and I still ask him to help me with things that I don't actually need help with. As they get older, they don't like to spend time with us -- trust me, enjoy it NOW! I will call my son down and tell him "I need you to make a pizza for you and daddy while I make mine". I continue to ask him to look for things, measure things, read directions etc. Same goes for cleaning and other projects around the house. I find that asking for help goes over much better than ordering him to "clean the bathroom". If I say, can you help me by getting the windex and going into the downstairs bathroom and cleaning the mirror. It gives him a mission and a challenge, and he feels he is "helping" rather than doing a chore.
I know this probably isn't exactly the answer you were looking for, but I also know by reading your profile that you are a busy, busy lady, and doing your best, so I suggest you get him active in being a productive part of the family and spending time with you at the same time. Take turns. Say to him "okay, we will go outside and play, but first, we need to get dinner started". Then always follow through, and just FYI, do your part first because they lose interest if they have had their reward first!:-)
Good Luck and keep up the good work!!! I love hearing parents who want to spend quality time with their kids, it isn't happening that much these days!!!