How many minutes should you spend warming up and cooling down when doing aerobics (lets say 30 minutes of aerobics--both high-impact and low-impact)?

I do about a 10 minute warm-up... combo of 5 minutes of stretching and 5 minutes of cardio... but when I've worked with a personal trainer they would always have me do about 10 minutes of cardio before the "main" workout...

My experience has been that most people develop their own "rituals" when it comes to warming up and cooling down... and everyone seems to have their "reasons" for what works best for them...

But for me anyway... 10 minutes or so before and 10 or so minutes after seem to work for me and my HRM confirms that for me...

5 to 10 mins is the rule of thumb...

If I'm going to run, I always walk briskly for 5 minutes before to warm up and walk briskly for at least another 5 minutes to cool down and then I stretch for another 5 minutes or so.

I only do aerobics or step or kickboxing using videos and for those, they usually come with warm up and cool down sessions which I've timed at about 4-5 minutes usually,

when i run i usually stretch a little in the locker room while getting ready...then on the treadmill do a slow walk while stretching legs for 3 minutes, gradually speeding up to a faster walk...then i do my running...granted, i run in intervals because it helps me manage my asthma better so i might run 1/4 mile and then walk a minute etc...and if i'm running high intensity ones, i build up speed slowly to the hardest ones...and cooldown is two minutes of slower walking, slowing it down gradually and stretching out my legs during that...it's worked for me for over a year now