As yall know, I've never been a fan of the inside of a gym, or those HUGE exercise balls. What I am a big fan of is technique and timing. It's more important to do an exercise correctly because if you do not, then you could end up hurting other areas of your body AND using the wrong set of muscles for the intended technique !! Squats and lunges are very important, but if done incorrectly can put a major hurt on the lower back and butt.
Webmd.com has a good 30 minute workout !!
Most of these exercises shown here can be done at home. If you have the weights, you can modify the location. Then again, weights are NOT as important as technique.
Always remember to stay well-hydrated. If you have done 20 minutes successfully.. can you do 30 minutes ?
The 30–Minute Fitness Blitz
Think you don't have time to work out? You do. It's the intensity of your workout that's key. A short–burst, high–intensity workout boosts your metabolism and tones muscles. Get moving with this 30–minute "quickie" routine that includes cardio and resistance training.
If you're new to exercise, over 40, have a health problem, or take regular medication, check with your doctor before starting a fitness program.
Frequency of Workout
Perform this 30-minute workout routine every other day, or do it two days in a row if that better suits your schedule. These are not hardcore bodybuilding-style routines where the high degree of muscular overload requires full rest to recover. For a healthy body, work out regularly and eat a healthy diet.