jtb790,
That's for you to decide. How much do you need to live your
desired lifestyle?
Here's a
spreadsheet that might help you.
You can edit all the yellow fields.
As an example from the spreadsheet, let's say you use 30-pip
stops, and don't like to risk more than 2% of your account on
each trade. You know from experience you can average 200 pips
of profit per month. You want to make around $12K per month
to cover your lifestyle.
This means you need a trading account of around $96K, and will
have to be comfortable trading 640K lot sizes.
If you assume something other than a dollar per pip because
of the currency pair(s) you trade, or you want to express lot
size in something other than $1k units, you can unlock the
spreadsheet protection and change the cell forumulas.