I'm not sure I can agree with Judie. Or maybe I am just too selfish to agree. I don't think that you should be aside everything that is "yours" while your kids are small. I think it is important that they are a priority in your world, but not your whole world. It's important for them and for you.
It really is your choice and you have to decide what is right for you. With four kids, you could have them (or at least one) in the 'kid' phase for 17 to 20 years. That is too long to put aside what you want to do for you. I always took time for things that I liked to do when my kids were young and I don't regret it at all now that they are older. And they turned out fine, if I do say so myself.
I think if you want to put other things aside and concentrate on them when they are young, that's great. But if that makes you feel resentful and like you are losing who you are as a person, then it's fine to have things that are just for you. Make the best choice for YOU and that will make you a better mother because you'll be happier.
And at the risk of really being controversial, you have a right to insist that your husband take his turn at being responsible for the children to give you a break.