1 Light therapy :- you sit a few feet from a special light box so that you're exposed to bright light within the first hour of waking up each day. It generally starts working in a few days to a few weeks.

2. Modify lifestyle :-

a . Make your environment sunnier and brighter.  Sit closer to bright windows while at home or in the office.

b. Get outside. Even on cold or cloudy days, outdoor light can help — especially if you spend some time outside within two hours of getting up in the morning.

c. Exercise regularly. Exercise and other types of physical activity help relieve stress and anxiety, both of which can increase SAD symptoms. Being more fit can make you feel better about yourself, too, which can lift your mood.

Normalize sleep patterns. Schedule reliable times to wake up and go to bed each day. Especially for fall-winter-onset SAD, reduce or eliminate napping and oversleeping.

3. Psychotherapy:- a.Identify and change negative thoughts and behaviors that may be making you feel worse.

b .Learn how to manage stress

c.Build in healthy behaviors, such as increasing physical activity and improving your sleep patterns.

4. Socialize. When you're feeling down, it can be hard to be social. Make an effort to connect with people you enjoy being around.

5. Take a trip. If possible, take winter vacations in sunny, warm locations if you have winter SAD or to cooler locations if you have summer SAD.

6. Medications if other things are not helping. 

a. Anti depressant, it may take several weeks to notice full benefits from an antidepressant. In addition, you may have to try different medications before you find one that works well for you and has the fewest side effects. so be patient.