Everybody feels sorry for themselves sometimes. It's normal to go there now and again. Problems arise though (as they do with all negative emotions) when you get stuck and those internal voices keep playing over and over like a broken record. Then it is time to stop, tell yourself, "This isn't working for me!" and make a change.
The best advice I ever got from a mentor of mine about self pity was this: "It's O.K. to feel sorry for yourself. Everybody does. If you are going to have a pity party, though, for God's sake, put a time limit on it!"
That was one of the best pieces of advice I ever got. Of course, it makes sense. Fighting emotions...feeling guilty...telling yourself to snap out of it...none of that works. Besides, problems only emerge when you end up stewing in your own juices. So, if you are feeling sorry for yourself, let yourself cry, kick, scream, mope, stay in your sweats, hide out at home, refuse to answer the phone, watch Netflix, eat chocolate, etc., whatever is your comfort! However, once you have indulged for a period of time, promise yourself that by such and such a time, you are going to stop the drama, pick yourself up, dust yourself off and get moving... whether that's going out for a walk, meeting a friend, cleaning out that closet or getting to the gym.
It never works to try to ignore or push away negative emotions. You can do them up big. Just put a time limit on them!