Having a neurological disease such as multiple sclerosis (MS) leads to difficulties in balance and gait with or without concurrent performance of cognitive tasks, hindering activity performance and influencing the possibilities for an independent lifestyle. The investigators have adapted a previously developed balance training program to a highly challenging program specifically directed to MS (HiBalance-MS). This program was recently tested and found feasible in a pilot study. The investigators will now perform a randomized controlled trial in people with MS, in order to determine the effects of the program. The hypothesis is that progressively challenging balance exercise programs that are specific to the balance control domains affected by MS will be effective to improve balance control, walking, motor-cognitive performance, activity performance and health related quality of life.