well, usually when i focus on my body, I try to feel it getting heavier and heavier
this mostly works for me
the principle behind the 61-point relaxation consists of focusing on each different part of your body at a time and making it feel heavy
it works nicely if you're not really the master of relaxation, but it can become boring in my opinion
if that still doesn't work, then your problem is not with relaxing your body, but your mind
you might be thinking too actively, and getting restless because of that
just try to daydream or to think about something happy.. it shall work nicely