If you have trouble noticing two things at once, or if you can do it, but feel overwhelmed when you do so, then just pick one to start with. Spend a lot of time with just that one thing. Then, start to add in just moments of paying attention to one other thing. Say that you have an easy time feeling your butt making contact with the support underneath it – make that like home base. You hang out at home base and just be with that, but then take small little trips into orienting land – short enough that you can still feel that contact under you. When you lose that sense of contact, drop the orienting and come back. If you practice this way you will likely develop more ability to multi-task with what your paying attention to over time.