How many pushups should I do in a day for optimal results?

[jboldeniv]

I know that I haven't worked out in a long time. I'm pretty old now, I get winded just going up the steps. Back when I was younger I could do 6 sets of wide-arm pull-ups, with about 30 a set. I have lost a lot of strength since then.

How many pushups should I do in a day for optimal results?