Researches at Northwestern University concluded that 45 minutes per week produced many of the same advantages as longer exercise periods, for older adults with arthritis.

Federal guidelines suggest achieving 150 minutes of moderate exercise per week to prevent premature death and serious illness. Participants who achieved the minimum of 45 minutes of moderate activity- such as brisk walking- were 80% more likely to improve or sustain high future function over the course of 2 years.

The moral of the story- even a little activity is better than none.