From the analysis, we can know that: ① If you have a cold, you can recover ahead of time by doubling your medication; ② Drink fruit juice, cola and other drinks instead of drinking water; ④ Adolescent smoking will not affect their intellectual development; ⑥ Low-carbon life: On March 27th, the World's "Earth Hour" activity day-families voluntarily turn off the lights for one hour, which has nothing to do with me. All the above are unhealthy lifestyles;
③ Maintain a happy mood and a positive attitude; People who meet the requirements of blood donation should voluntarily participate in blood donation, which belongs to a healthy lifestyle.
Therefore, choose: B.