​What are some methods to improve adherence to physical activity?

​Currently only 33% of adults get regular physical activity per recommended guidelines.
There are a few different tactics to use to increase physical activity:
Informational interventions are one method used to try to increase physical activity.
They do so by increasing public awareness of the importance of physical activity and the benefits of engaging in physical activity.
One example of informational interventions are mass media campaigns. Mass media campaigns increase awareness of the importance of physical activity but are not successful at actually getting people to engage in physical activity.
"Point of decision" prompts are another example of informational interventions and are more successful at behavior change than mass media campaigns.
Behavioral and Social Interventions
Behavioral interventions attempt to teach people the skills they would need to engage in physical activity, whereas social interventions aim to create social environments that would enable successful behavior change and maintenance.
One example of behavioral interventions are school-based PE programs. These programs increase physical activity during school hours but do not increase physical activity after school hours. Thus, kids are not taking what they learn during school and using it later
Social Interventions are interventions such as developing a "buddy system" or workout partner. Having a workout partner does help an individual adopt and maintain a physical activity program.
Environmental Interventions
Environmental interventions are when the environment is changed to make exercise more likely. For example, having sidewalks and parks-places to exercise-increases physical activity.