You express your frustration and disappointment so clearly and my heart goes out to you.
Have you ever flipped the job thing around and thought 'They're not good enough for me'? The money may be good but are they jobs you passionately want, ones that suit your nature? For example, if you're a deeply thoughtful caring person towards others, are you applying for technical positions rather than positions relating to personal care? If technology seriously excites you, are you applying for positions that involve making phone call after phone call at a call centre? What would you really love to be doing? You can imagine an interviewer thinking 'I don't think I've ever met anyone who was more passionate about this job'.
Personally, I was seriously stressed about applying for a job after 16 years of being a stay at home mum, so you can imagine there was a pretty significant gap in my resume. It had been about 23 years since I'd worked in age care when I applied for a job as cleaner and kitchen hand at a local aged care facility. As a way back into the industry, I wanted that job passionately and my cover letter reflected this. Something like 'I understand that quality of life can be dependent on our environment. Mental well-being and a sense of respect is felt by those who receive a service which reflects care in every possible way' and so on. I believed in everything I wrote and the interview was a chance to prove it. Getting the job sent my anxiety levels up as I dealt with not only learning a routine with a huge number of fine details to remember but dealing with such a large number of new faces also tested my self-esteem.
In regard to physical well-being: Have you considered asking for a small loan from family for a second hand exercise bike or a cheap new one? They're much cheaper than treadmills. A few years back, I needed to lose weight but couldn't do the walking thing because of calf pain. With the exercise bike, it allowed me to exercise pain free whilst the display did the calculating when it came to how many kilojoules I was burning off. A few toning exercises from a book I'd found and things began to finally take shape in more ways than one.
The jobs we apply for or the modes of exercise we undertake don't need to be terribly glamorous in order to facilitate a sense of change and greater well-being. In compromising and meeting life, friends and family half way, the middle ground can become the point opportunity.