Physical activity (PA) is a modifiable factor that may have an influence on the course of Parkinson’s disease (PD). This study aimed to apply a simple behavioral intervention to encourage PD sufferers to increase their everyday physical activity and assess which parameters of motor functions will be improved. The research covered 50 PD patients (28 men and 22 women) aged 40-81 years (65.38 ± 9.23), with a duration of the disease 2-4 years, in stages 1-3 on the Hoehn and Yahr scale. The patients were randomly divided into two groups: the experimental group with behavioral therapy, and the control group without intervention. During 12 weeks the patients from the experimental group had five phone conversations. Each conversation lasted 15 minutes and was an interview about the subjects’ physical activity in the last month. The results were assessed by the Timed Up and Go test (TUG), Unified Parkinson's Disease Rating Scale (UPDRS) – part III, FIR (Functional Index “Repty” – own modification of Functional Independence Measure (FIM)), Functional Ambulation Category (FAC) and International Physical Activity Questionnaire (IPAQ). The results showed that spontaneous physical activity increased in the experimental group and motor functions improved. Physical activity improvement depended on age, body mass index, and gender.