For beginners, monitoring improvement is a good way to stay motivated. While achieving a new personal record at each race you sign up for might not be too difficult to accomplish at first, the longer you run, the more challenging this will get.
Goal setting is always important, but expecting to set a new PR at every race is unrealistic and can cause unnecessary stress. To relieve some of the pressure that racing can cause, pick a few events each year that you run only for fun. Keep your expectations low, and don't worry about your time. Concentrate instead on enjoying the activity and celebrating the sport you love, which can also help to avoid burnout.