I find it close to impossible to walk and chew gum at the same time. You can imagine the grief singing and playing guitar at the same time are for me. I play guitar and only sing back up vox in my band and it's taken me close to a year to train myself to be coordinated enough to just be able to do that. The only thing that will help is practice and time. Eventually you'll get to a point where you are comfortable enough to do it.