How to get strong and in shape in three months?

First off, I want to say I don't want to lose weight. My weight is fine, and I wouldn't mind gaining a little more. I just want to get strong and be really healthy. Right now, I am flabby, weak, and don't have good stamina. My diet is fine for the most part. I drink water all the time and am a vegetarian. I exercise off and on, but I have a problem with keeping up with it because I never see a lot of results. I do weights, cardio, pilates, yoga, and so on, and have tried lots of stuff, but I just get so unmotivated when I feel like what I am doing is pointless. For instance, I did high impact cardio and weights for 30 minutes 3-4 times a week and yoga for 40 minutes once a week for three months, and there was no difference in my measurements or anything I could tell. Could somebody give me a detailed routine that I could do for three months that will get me in shape enough to see some results? I know I probably won't be able to get in the shape I want in three months. I just want to see SOME kind of results!