Occupational sitting time in white-collar workers represents a prominent contributor to overall daily sitting time, which is associated with various health risks. Workplace interventions intending to reduce sitting time during work typically focus on replacing sitting with standing. The aim was to investigate and compare actual and desired proportions of time spent sitting, standing, walking, and doing physically demanding tasks at work reported by desk-based workers. Cross-sectional data were collected from German desk-based workers (n = 614; 53.3% men; 40.9 ± 13.5 years). All were interviewed about their self-reported actual and desired level of sitting, standing, walking and physically demanding tasks at work. Desk-based workers reported to sit 73.0%, stand 10.2%, walk 12.9% and do physically demanding tasks 3.9% of their working hours. However, the individuals desire to sit, stand, walk and do physically demand tasks significantly different [53.8% sit, 15.8% stand, 22.8% walk, physically demanding tasks (7.7%), p < 0.001]. The present data revealed greatest mismatch between the desk-based workers’ actual and desired time for sitting and walking. Health promotion programs should offer not only options for more standing but also opportunities for more walking within the workplace setting to better match workers’ desires.