When I'm at rest, I have a heart rate of about 66-69 bpm. But when I get up and simply walk around, it goes up to 113 bpm. I used a heart rate app on my phone to see what my bpm was, so not sure how reliable it is. I'm 25, don't exercise much but don't drink or smoke in excess. Somedays my heart rate is normal but today it's higher. Could this be an issue or is it something minor?