Yoga, Meditation are sure ways. But then there are other ways to reach the state (without calling them yoga). I guess by white space, we mean peace, emptiness, stillness, mind not wandering, not thinking too much, not worrying too much. All these are signs of a mind that is not fulfilled, not satisfied. So i guess first is to think what is it that you worry about…and why. Sometimes in life, at different stages of life you find things missing from you, you feel incomplete.
List down what your goals are, what you seek from life, list what is it that you want to do. Also list the Noise factors..what is it that is disturbing you. Put these both in front of you. May be you need some help to reduce the noise factors in your mind. Constant hankering of your parents for you to get married could be that noise. Not having a particular skill that you need at job could also be that noise..may be last weeks’ fight with your friend is bothering you, or perhaps its not earning enough so you could travel is the reason. Whatever it is, lay it open and then discuss with someone who could show you alternative ways.
Listing them down itself should start making some grey space.
I know you said ways besides meditation, but think of it like this..sooner or later you realise material things, and even people are not the reason for the noise in your head..if you could make them not-matter to you..you get instant white space. It is worth trying .