Some things to avoid while taking atenolol or Tenormin:
From WebMD.com (http://my.webmd.com/content/drugs/4/4046_1189.htm?lastselectedguid={5FE84E90-BC77-4056-A91C-9531713CA348})
  • Use caution when driving, operating machinery, or performing other hazardous activities. Atenolol may cause drowsiness, dizziness, and blood pressure changes. If you experience drowsiness or dizziness, avoid these activities.
  • Tell your doctor and dentist that you are taking atenolol before having surgery.
  • Use alcohol cautiously. Alcohol may increase drowsiness and dizziness while taking this medication

Another note from a taker of atenolol, and this took me by surprise because my doctor didn't mention it: this medication will lower your heart rate and if you're on a Cardio exercise program where you're attempting to reach a target heart rate, you'll have to adjust your target heart rate downward. Probably should have been obvious to me, but my first cardio workout after taking my first dose of this medicine was a little disconcerting.