I was to get in shape but I have no motivation to do so?

I'm 5'7" and around 135lbs. I understand that for my height, I am at a normal weight. I don't want to lose weight, I just want to improve my health. I rarely exercise and get tired fast when I try, and I lose motivation. It's hard to eat healthy because my parents say it's too expensive, so I eat a lot of processed and canned ****. I try to eat the healthiest junk we have. I need help to find motivation to work out and get fit. What could I do or think to motivate myself to get in shape? What motivates you? Thanks :)