How do I section off my savings account to save for a special thing? Instead of opening another acc

I am trying to keep my savings account in tact, for recon purposes. I want to keep a section of this account to record an amount of money saved for special purposes. I want to keep them saved into the same account for recon purposes.
I feel sure that I am not the only one that has an interest in doing this. I just need to know how to do it. I could be as simple as labeling amounts of money in a certain way when posting it.