Is there any way to improve skin tone after outdoor activities?

I'm concerned that my facial skin looks dull due to frequent outdoor activities. My cheeks, forehead, and cheekbones are particularly dull, making my overall skin tone look dull and aged.

I'm finding it increasingly uncomfortable to look in the mirror. Is there any way to reverse or improve my skin tone? Is it possible with home remedies or if I need dermatological treatment? Please share your experience and advice.

Sunscreen is I think about applying it consistently every day, but I'm actually busy and can't apply it... What do I do when I go out and can't apply it?