spend time with family or friends, your significant other, or just focus on yourself. working out always makes me feel good. as in just jogging. take a couple days off to just focus on yourself & relationship. go on a date.
Life deals us all cards we are not sure we can deal with. But at the end of the day when you think you can go 1 mile... in actuality you can go 5. Keep your head up and know that people CARE about YOU! And no matter what you are a person who matters in this world.
Sounds like you might be experiencing depression, or SADD (seasonal affective depressive disorder, I think). Do you live where it is sunny most of the time? If not, get a SADD lamp, it will give you the light quality that you need to cope with SADD. If it is typical depression, try St. John's Wort or get a diagnosis from your doctor and seek help.
Develop a strong relationship with Christ. My relationship with God has literally been the best thing in my life! The Lord has done things in my life that I never could have imagined! I can honestly say that I'm most happy when I'm in church, or worshiping/praising Him. It's just amazing what God can do in your life :) God loves you, and a personal relationship is what He wants to have from you. And He won't forsake you :) God bless!
If you want to DO something to end your depression other than thinking about it, go be of service to someone in need. It's hard to feel bad while fixing the gate old lady next door, giving a ride to the store for someone without a car, visiting a disabled veteran in the hospital. If you really want to end your depression, be of service to someone else who needs help. It will not only boost your self esteem, but it will bring joy to your life as you ease the burden of someone less fortunate than yourself.