Actinic keratosis is a direct result of repeated sun exposure. It doesn't show up until later years and can often be a surprise when it does.
Besides the displeasing appearance and feel, actinic keratosis can be a suggestion that skin cancer could follow. Not all AKs become skin cancer, but it's smart to have them checked by a dermatologist who knows what to look for. Without a trained eye, it's difficult to impossible to self diagnose whether a rough raised area is an AK or a beginning stage skin cancer.