Strike while the iron's hot (打鐵趁熱，趁勝追擊)

"Strike while the iron is hot." (打鐵趁熱，趁勝追擊) means " to take action immediately in order to have a better chance of success."

Eg. You may not get a better offer - I'd strike while the iron's hot, if I were you.

When you have a customer on the phone, strike while the iron is hot by offering special discounts on certain items.

take as it comes

"take as it comes" means "to deal with something as it happens, and not plan for it."

Eg. At my age you can take every day as it comes and not try to guess about what will happen tomorrow.

Everyone has their cross to bear.

"Everyone has their cross to bear" means "an unpleasant situation or responsibility that you must accept because you cannot change it.

Eg. I hate my red hair and pale skin, but everyone has their cross to bear.
Someone has to look after mother and because I live the closest it's a cross I have to bear.