My 2 cents (what works for me):
Keep on hiking or other aerobic exercise (running, stair climbing, etc.) Don't add extra pack weight to training, the goal is to get your heart rate up for extended periods of time. Just hike with what you need for your training hikes. Do longer training hikes, or do your current hike twice in a row once/week, as you get closer to your date in August. If running, do intervals and hills.
I wouldn't bother with squats, lunges and pushups.
2 weeks before your Whitney date, taper your exercise. You want to be well rested before the hike. Do half your normal workout for 1 week, and very little during the week before Whitney.
Don't forget not to over-train, to prevent injuries, work in some rest days, 2/week at least. It sounds like you're training 6 days/week. It might be better to train longer aerobically, but fewer times/week.
The Diamox dose is 125 mg. twice/day, start at least 2 days prior to Whitney. If you have allergies to medication, make sure that it's safe to take. Diamox increases your respiratory rate and depth, increasing your oxygen intake, and can be very helpful for those who don,t acclimatize well.
Something else that will help your success is a positive mental attitude. Doing long hikes prior to Whitney won't only help you physically, but also mentally. If you can do your regular hike back to back (or other long hikes), then you will be better mentally prepared for Whitney. Your body will be used to long hauls and your mind too.
Starting in the dark can also help mentally, as you can't see how much farther you have to go for the first couple of hours.
Good luck and enjoy.
