How can i stop feeling sad about having to diet/exercise to lose weight?

Make it fun: Join a group, go to a local ymca, get some support and encouragement. If you do enough aerobic exercise every day you should form new habits and it will also elevate your mood and self-esteem. Keep at it and don't quit! you will feel better.

Gratitude: Sadness is a sign you have not accepted where you are - replace this with gratitude for being given a challenge you can work with. Sadness is victim thinking serves no purpose and drains you. Gratitude is a choice thinking - life is about choice so set goals you can work on. I do a exercise if I am sad. (taught by sri srravishankar) sniff out sadness -sniff twice -http://www.Artofliving.Org.