Just a quick thought on the bicycle point. I believe that it would be greatly beneficial for a person, who is in position to do so, to ride a bike to work for a few months. Every day, regardless of how they feel, or how much they don't want to.
Obviously, if you have to take your kids to school and won't have time afterwards to make it to work on time, or over 5-10 miles of a commute, this won't be very easy to acheive.
But, if it is only a matter of getting up earlier and the effort of the ride, that prevents a person from doing this? I challenge you to do it, listen to some uplifting podcast en route and stay committed when you really don't want to.
Possibly even journal some of your thoughts after your commute..
There is a quote, "Adversity toughens manhood, and the characteristics of the good or great man is not that he has been exempt from the evils of life, but that he has surmounted them." Now, this month or two of a bike riding commute might not be considered an "evil" of life, but if a person is living an average life with all the luxuries an average life provides today? An extended amount of time dealing with this commute challenge, especially getting over those days when you really don't want to do it, can have a very positive impact on their life.
What would one of these studies say about a person who purposely does something in their life to cause more struggle?