One of many ways to learn to relax your breath and make it naturally deeper is to breathe in one count and breathe out one count. Next you raise the count to two and go as high as you can and than lower the count. I prefer to do something with this in the lines of walking or other basic movements and if you feel over time that you have gathered a lot of tension to the surface with your breathing count simply move to one and one again between the raises and the body will naturally clean itself of the tension due to the over or under breathing.
This is the same idea as raising the speed of your breath before an effort to make yourself ready and less stressed in the form of an action before the tension can come in and effect us in a harmful way.
Enjoy the weekend. Take your kid outside.