I would like to mention this particular quote which is actually about investment but I think sometimes it applies to forex trading as well. The quote was said by Paul Samuleson, the first American economist to win the Nobel memorial prize in Economic Sciences. ”Investing should be more like watching paint dry or watching the grass grow. If you want excitement, take $800 and go to Las Vegas.” This quote implies that we need to be patient and plan ahead for the future more than the instant gratification. One should not get into forex trading hoping to get rich overnight. They should have an attainable and realistic goal for the future and must put up with the boring task of analysing the charts looking for a favourable position which might actually feel like waiting for the paint to dry.
Another favourite of mine
The goal of a successful trader is to make the best trades. Money is secondary.
Another that I really like
There is a time to go long, a time to go short, and a time to go fishing
"The expectation that you bring with you in trading is often the greatest obstacle you will encounter.” This is the quote that I always keep in my mind while trading in forex.
“When you have a dream, you’ve got to grab it and never let go.”
This also applies to trading: when you decide to do something, you do your absolute best to complete it.
Just above my monitors I have a framed quote:
Take the risk or lose the chance.
It reminds me to keep things in perspective:
Life is short and one day there won’t be any time left to take risks.
That doesn’t mean we should throw caution to the wind, of course, and especially not when it comes to trading the financial markets.
However, in pursuit of our goals we must be willing to embrace risk.
As Niccolo Machiavelli says in The Prince, “Never was anything great achieved without danger.”
May you be able to accept your losses, celebrate your winners and always enjoy the journey regardless.
Dan
My fav one-
“In trading/investing, it’s not about how much you make but rather how much you don’t lose” by Bernard Baruch.
“The key to trading success is emotional discipline” by Vic Noble.
Nice quote 
Trading requires emotional discipline.