Memory could be operationally defined as the number of words recalled from a word list with 20 words that participants are asked to memorize. The no exercise group would be asked to avoid physical activity that raises their heart rate for that month and would be given the same memory test before and after the 1-month period.
Tall people are likely to be outgoing.
Height could be measured with a standard measuring tape in feet and inches. People who are talking on cell phones do not drive safely. We should probably choose just one form to be consistent. If we ignored that factor, the results could be quite confusing to interpret. We would need to decide if talking on the cell phone meant that they were talking while the car is moving too.