This study aims to examine the effects of low-intensity, combined physical-cognitive exercise on cognitive function of older people with mild cognitive impairment (MCI) and identify the mechanisms by which this exercise protocol exerts cognitive function. Older adults with MCI will be recruited to either an exercise or a control group. Low-intensity, combined physical-cognitive exercise will be prescribed to the exercise group 3 times per week for 3 months while the control group will maintain their routine lifestyle. It is hypothesized that at the end of the trial, participants in the exercise group will demonstrate significant improvement in cognitive performance and circulating biomarkers compared to baseline and the control group.