You work extremely long hours and get accustomed to rejection I'm afraid. Teaching prep takes less time when you haven't got all new courses to prepare, so that will get easier. On the grants, get any feedback you can, improve it, tweak it to fit new requirements, and apply to another funder. In my field a 20% success rate in grant applications is doing pretty well and you have to recycle ideas in new and improved formats. It can also be helpful to try and work together with a more senior academic with a good track record in getting funding on a joint application, to see what they are doing differently. But it's also worth knowing your strengths. If you aren't someone with lots of ideas about your future research agenda, but are a great teacher, then look carefully at what your employer is expecting - could you instead apply for funding to do pedagogical research and still have it count to whatever target you need to hit for instance?