About atypical moles and melanoma?

I'm 20 years old and I recently spotted a strange looking mole on my arm. It was concerning, so I went to the derm and had an excisional biopsy. I just got back the results and she said it was benign (thank god) but also atypical, which means I have a higher risk of skin cancer. My question is, how high a risk? Is it still fairly unlikely as long as I take care of myself (sunscreen, good diet, etc) or is it something I should plan on in the future?