When someone tells you that you don’t need to worry about something, does it ever stop you worrying about it? Probably not.
How about if God reminds you there’s no need to worry? Although I believe in God and trust Him for me future, it is still hard not to worry about some things – after all we are all still human.
However maybe if we took God at his word, and put our faith fully and unquestioningly in Him, we could remember to live today, instead of worrying about what tomorrow may bring.