Sometimes running sucks. And by sometimes, I mean a lot of the time. I would estimate that maybe 25-30% of the time running actually feels good, and the rest of the time I finish and gripe about how terrible that run was. I will say, however, that once the run is over I never regret having done it - even if it was a bad run.
Running is hard. There's no magic formula to make you faster or better. You just have to keep running. Period. When I started running six years ago I was in pretty good shape, but I had never run more than two consecutive miles in my life. The only way I was able to build on my mileage was to do it. You have to log the miles over and over again.
There is no shortcut. Some days I finish running and my knee hurts, my hip hurts, I'm tired. Some days I can't get motivated because it's cold, it's rainy, or I just don't feel like it. I think it's okay to take a break, and I try not to beat up on myself. But the only way to be able to run is to suck it up and do it. It hurts. Your knees will hurt, your body will hurt, you will push the limits of what you ever thought you could do. And at the end of the day it's hard. Just suck it up and do it.
Running is as much emotional as it is physical. Having the motivation to keep going is most of the battle. I've posted before about how hard motivation can be to come by, and it's an ongoing battle. But for every 3-4 runs that don't feel the way I want them to, I have that one run - that one where I feel great the whole time and I run faster and harder than I've ever have before. That is when it's all worth it.
It takes a while to get there. You can't start running on day one and feel like Shalane Flanagan. But put in the work and the effort, and it gets easier. I promise. It may take weeks or months, but it does get easier. In the meantime buy yourself some new shoes, some cute running gear, and put your miles on the calendar so you'll be reminded of how many you're supposed to run and motivated to do the work. It won't always be pretty, but it will always be worth it.