Sometimes if there is some sort of a block in my practice, but I can't find exactly what, I find it helpful to switch to another style of meditation. For example, walking meditation. This can just be a mindful walk in the park, for example. Just to walk and enjoy the wind on my face, the ground beneath me and the nature around me can be very calming already. And it is very unlikely walking meditation will tense up your body. After that sitting meditation may also be much easier and the sense of ease may grow bigger.
Against depressive mindstates, often metta meditaton works much better than mindfulness because a big part of depression is rooted in ill will & non-acceptance.
Do you practice these types of meditation? I would really recommend it. I hope it can help you. Aside from that, and I should have actually started with this - if you are really depressive, you should look for more qualified help.
I know you'll be fine eventually
This feeling won't last forever.