You don't need to be able to do this much faster, but you should also be able to do 4 miles in about 28 minutes and run at least 9 miles without passing out.
Step2
Do 100+ pushups in 2 minutes.
Again, it's not so important that you shatter this (though that's great) but that you are able to take a rest and repeat it 3 or 4 times.
Step3
Do 100+ situps in 2 mintues.
Same as pushups.
Step4
Do at least 15 pullups
But 20 is better and 25 is better than 20. There is no upper limit on pullups, so get good at them.
Step5
Swim 500 yards in around 9 minutes.
Remember that you are not a sprinter. As soon as your popping your 500 yard time under 9.5 minutes turn your focus towards your 1 mile and 2 mile times in fins.
Tips & Warnings
BUD/S is damn hard. When you think you've done enough, do more.