Well, the school year is about to start and throw me off a bit, but the BEST I have EVER felt as far as alert, stress free and high energy was when I was doing yoga in the mornings frequently-and I'm not a morning person! I used to do it at 4pm when I was single.
But now, with 3 kids, I feel best if I GO TO BED EARLY, get up early enough to be alone and eat something healthy and drink some coffee (because i"m not a morning person and cannot just hit the mat straight out of bed) and THEN do an hour of yoga before everyone wakes. I too have been limited to DVDs for the past few years. I feel much better even doing this a couple times per week-but for a while during the winter I was doing it 4 mornings a week, every other day, and after a couple of weeks I felt AMAZING. Best I've felt since I gave birth to my 1st 5 years ago.
Meditating: It's gotta be amazing, but I've been trying for 15+ years and do not have the mind control. I always tell myself I'll study it properly one day and get the knack.....I CAN'T do it. Even when I was guided by experts at the end of advanced yoga sessions and I should have been all "receptive" to peace...Nope. I admire anyone capable of calming their mind for even 30 seconds.
Pick a time of day when you will be undisturbed. Make sure you are generally well rested and eating healthy food, and YES, the regular yoga will have you feeling energized and amazing. I use lots of other workouts and the gym just to shed pounds and maintain weight, but nothing makes you FEEL as good as yoga. Although, I have to be slim to do it. If I have extra pounds, it doesn't feel so great, so I burn those off and then go back to yoga :)
If you're sort of new to it, Rodney Yee's Gaiam videos are great and there are various lengths. He's slow paced and easy to follow, but does thorough, challenging routines, and the better you get, the more challenging you can make it.