With data from automated counting stations and controlling for weather and calendar effects, we estimate the isolated impacts of the Covid-19 pandemic and subsequent government intervention (contact restrictions and business closures) on walking and cycling in 10 German cities. Pedestrian traffic in pedestrian zones decreases with higher local incidence values, and with stricter government intervention. There are ambiguous effects for cycling, which decreases in cities with a higher modal share of cycling, and increases in others. Moreover, we find impact heterogeneity with respect to different weekdays and hours of the day, both for cycling and walking. Additionally, we use data on overall mobility changes, which were derived from mobile phone data, in order to estimate the modal share changes of cycling. In almost all cities, the modal share of cycling increases during the pandemic, with higher increases in non-bicycle cities and during stronger lockdown interventions.