to me this song is about someone who is just coming near to the end in a period of depression. he is supporting her saying 'when they (whoever they may be, whether they be the voices she hears or the people depressing her) say you aren't strong, you are (you aren't that weak). they are saying she has to get out if it and to be happy again. there isn't anything left to lose/fear - shes lost everything already, so they are convincing her to try and get up again
to me this song is about someone who is just coming near to the end in a period of depression. he is supporting her saying 'when they (whoever they may be, whether they be the voices she hears or the people depressing her) say you aren't strong, you are (you aren't that weak). they are saying she has to get out if it and to be happy again. there isn't anything left to lose/fear - shes lost everything already, so they are convincing her to try and get up again