Vicious cycle- how to motivate yourself when you feel like you have nothing left to fight for

Hi, I feel bad posting again, but I am really struggling. I have so many issues (burnout, stress/anxiety, eating issues and urgently need to gain weight etc) and I realised part of me just doesn't want to get better as I feel like I have no goal and nothing I like doing anymore. I had such a strong wish to do a PhD but now that I have offers, I felt no pleasure when I got them, just stress and the feeling that I must be a liar and none of them feel right for me. Having to decide what to do is giving me further agony- I desperately just want one of them to feel right and to motivate me so that I can have something I enjoy and want to work towards again but it all feels wrong for various reasons... but I have no idea what to to if I don't accept any of these. I don't like my job and there is nothing else I ever liked or am good at. 

The other thing that used to motivate me is my love for hiking and outdoor activities (running, cycling, riding etc), but due to injuries I haven't been able to do these for 3 years now and I am too underweight now anyways (which makes it a little easier to bear that I am trapped though of course it is not helping).

I feel like the 2 things that I love science and hiking are outside of my reach or I just don't really seem to care anymore. I am very goal orientated and I feel like I need something I believe in or some goal to work towards to get myself motivated to keep going and to try and break free from all of my problems- but at this point I have given up and don't know what I am still doing on this planet. I don't feel like there is anything left. It's sad and pathetic.

I'm so sorry for writing such a depressed post. I don't know what is wrong with me but I have 0 energy and fight left. I just want to disappear.