The effort you put in is admirable, Marijke! Thanks so much for sharing. A word of caution to the sit-ups. While they also train the abdominal muscles, it's the (invisible) iliopsoas muscle that gets the most out of it.). If strengthening the abs is a main objective, switching from sit-ups to crunches might be an option. The advantage: you don't need to worry about your lower back. Its intervertebral disks can get too much pressure from situps.