Something I'm pondering

Today one of my patients was talking about her children and how when they were little she tried really hard to be happy around them.  As part of raising them, she felt this would give them the best environment and apparently they turned out pretty good.
It got me thinking though, about how I am around my kids.  Do I show them joy (which I think is more important than happiness) or do I show them stress?  Unfortunately, lately I think it has been more stress.  I feel I used to stop what I was doing and play with them, dance with them, sing with them...take time to be with them.  While I still am with them, I am often cleaning or cooking or working on the computer or clipping coupons or or or...  The list goes on and on.  How often do I actually sit on the floor with them and play or color or goof off?  I honestly don't know the answer.
I grew up with a single mom who was devastated by the loss of my dad leaving.  It has shaped me.  I am the one who takes care of people.  Rarely do I let someone comfort and care for me.  I think it is a gift to be a listener, a gift God gave me that has helped me in my work and life but sometimes you do need to lean on others.  So the question is, how much do you let your children see that.  Do you lean on them sometimes or should you always be strong and stoic? 
I don't necessarily feel I should shield my children from all of my emotions.  If I am upset about something, do I hide it?  Sometimes I do and sometimes I don't.  Do they see me cry?  Yes.  Do they see me laugh?  I hope so.   But how much should I show them?  I don't want to hide my emotions so much that they think they have to grow up and not lean on people but I don't want them to grow up thinking they have to take care of me and my emotional issues or hide from me things that upset them b/c they think it might upset me (which I have done a lot with my mom).
Where is the balance?  I really don't know.  But I feel I can use some improvement in this area.