I really like Paul's advice in Galatians: Walk in the Spirit and you won't be indulging the old nature. It's a DO and not a DON'T.

Most of us can only do one thing at a time anyway. If what we do is toward God (memorizing Scripture is great for OCD, for example), we can't be simultaneously occupied with other things.

I've not been diagnosed with OCD, but we all battle with obsession and compulsion on some level. For me it helps to be very deliberately occupied with something holy and good. The mind set on Christ is free!

Some degree of OCD is common with my form of autism (Asbergers syndrome) and simple disciplines like scripture memorization and verbal "put loud" prayer helps me.