What two things should you consider when you determine the intensity of your workout?
your available time and interest
your strength level and eating habits
the activity and your fitness levels
the location and your starting point

  your strength level and eating habits, knowing what you can do is impotent you don't want to over work yourself. eating also plays a big part in this, eating the wrong things can harm your work out.
  the activity and your fitness levels,same as the first part. 
 

Iwould say c. take responsibility for your behavior