How long and how far you run will depend on your fitness level and running goals, but in general, most beginners do well running 20-30 minutes at a time, a few times a week. You certainly don't have to run every day, so include rest days and cross-training like cycling into your week. And if 20 minutes of straight running feels tough, adding in walk breaks (think two minutes of running, followed by one minute of walking) can make things more enjoyable.