We conducted a comparative user study in order to analyze the effects of walking on text reading and target selection. 16 participants took part and walked on predefined routes while reading text and selecting targets on a mobile phone with their finger. We varied the size of the text and targets from standard sizes to 120% and 140% as we assume that such an increase would compensate the negative effects of walking. Furthermore, we were interested how extensively the size of text and targets should be increased when considering the tradeoff between their size and available screen space.