In a quasi-experimental study with N=181 chronically ill and multimorbid patients in a multi-week hospital stay two measurement time points at admission and discharge were collected. The main aim of the study was to promote mental health through two targeted psychological interventions and psychosocial support by means of an intervention drawing upon recommendations from the Deutsche Pneumologen Gesellschaft e.V. ("DGP") or the "Extend Yourself, Action Plan, Selection und Expect The Best - EASE" approach developed by Cacioppo and Patrick (2008) in comparison to a control group, which did not undergo any intervention but received psychosocial support as usual "Care as usual"; CAU). While the main aim was to test effects on stress indicators such as anxiety, depressiveness and loneliness, the study also investigated the associations, and potentially, the causal relationships between the two short-term psychological interventions and symptoms of anxiety, loneliness, depression, and self-efficacy. Interventions on anxiety, loneliness, depression, and self-efficacy can provide insights into how these factors interact and influence each other in the context of chronic illness and multimorbidity during a several week hospital stay. Findings indicate that the two interventions did not differ significantly but depending on the outcome they have differential effects. With mediation analyses, social support appeared as a significant mediator in the relationship between self-efficacy and depression between two measurements. Given the observed gender differences and the differential impact on anxiety and depression, the psychosocial support provided by interventions should be individualized to address specific mental health issues, like anxiety or depression and demographic factors like sex. In general, all patients improved over the course of the hospital stay, and additional psychological interventions can help those who are responsive to social support mobilization. This calls for dyadic or social network approaches in addition to pure individual interventions, which should be investigated in further research