Getting "Started" for the Third Time!

Hey guys! I'm looking for some support and tips.
Quick facts: I'm a full time college student, I work part-time, I walk or bike everywhere, I'm vegetarian, and I'm a senior in high school.
I plan on going through another 8 years of college and then going to the Veterinary Corps.
I've been here twice before. I've been absolutely wonderful at this- I lost 15 pounds and was close to my goal weight then I quit. Now my goal is to get healthier and fit. I walk at least 6 miles every weekday and I eat most of my food at home. I just need help making days that are tough seem not so disastrous and running tips. I wanna make running a habit of mine like biking is. If anyone has any tips or ideas on that or balancing the typical stressed college load along with life, please friend request me. I'll gladly accept any support and I do my very best to return it!

Thanks!