i made it a priority to get my 1/2 hour workout in. i explained to DD that excercise time was mommy's time and that she had to play alone for that time. it took a couple of weeks of her trying every excuse in the book but i did stand my ground and let her now she could join or play on her own but had to leave me alone for that 1/2 hour. some days didn't go as good as others but for the most part after a couple of weeks she learnt that i wasn't stopping to give her the attention she was trying to get and she gave up and now leaves me do my thing. i will talk to her during the workout, encourage her to join and even hold her hand if that is what she needs. she also gets 1 chocolate egg while i am working out (now most days she will ask me if i am doing my excercise yet so she can have her egg)
it sounds mean but i really needed that time to me and she gets a lot of one on one time both before and after the workout. and also i wanted to model to her good fitness habits (we are active all day but this is the time she sees me making it a priority) and the fact that *I* am a person with needs as well.
these days i have been doing treadmill during her 1/2 hour show she is allowed to watch in the mornings and then i do another short treadmill after she has gone to bed.
my daughter is also 3
good luck to you