Couch to 5K Update

I just finished Week 5 of the Couch to 5K plan that will hopefully have me running 5 km (3 miles) in half an hour. This week I completed my first 2 mile run (in 20 minutes) with no walking. I did my first 2 mile run on Wednesday, and then I did another 2 mile run this evening. On to Week 6 next week! I am a bit confused as to why the first two workouts for Week 6 are actually easier than the 2 mile run...but the last workout is a 2 1/4 mile run with no walking. I am starting to actually enjoy exercising - I am beginning to notice some of its benefits. I feel like I have more energy overall and I am just feeling better in general.