There is a difference between Tough and Rough. When something is tough, it means it's strong and durable; not easily broken or cut, capable of great endurance; sturdy; not quickly influenced, unyielding, unbreakable. While rough means harsh, fuzzy, unequal, and unfinished. Giving examples; Rough driving is bad driving, while tough driving is good driving; Rough weather is stormy or tempestuous or very windy but a tough weather is tenacious, persistent, stubborn and cohesive; A rough temper is sharp or harsh but a tough temper is controlled; A rough fighter always looses but a tough fighter always win.
Some Christians pray Rough, while others pray Tough. Rough praying is praying from your head but Tough praying is heartfelt & fervent (James 5:16). The opening scripture tells us to pray without ceasing meaning you have to spend quality time alone with the Holy Spirit. The amount of time you dedicate in your communication (prayer) with the Holy Spirit will determine the speed at which Angels will respond to your prayer requests. Tough praying is not necessarily shouting audibly but it's boiling all over and it starts from the inside. Paul was somebody who understood prayer and its power. Prayer was a part of Paul's life, you cannot really be a good Christian and not pray, just like you cannot have a good marriage if you don't talk to your wife.
The Amplified version of our text scripture says "be unceasing and persistent in prayer"; Praying tough is a persistent prayer. Paul also in Colossians 4:2 said to "Continue steadfastly in prayer"; the word translated, "continue steadfastly," is translated as, "persist in, adhere firmly to, or remain devoted." It carries with it the idea of dedication. Persistence in prayer is not an option for the Christian. It is an order from the Lord Himself; .....that they should always pray and not give up (Luke 18:1). A person who is persistent in prayer does not necessarily have to pray for a long time. Persistence means not giving up. What you are persistent about, you'll be passionate with it. Persistent prayer is passionate prayer, praying tough is also praying passionately.
Praying tough is the pipeline of communication between God and His people, between God and those who love Him. Be tough in your praying, it produces results quickly and settles the matter but rough prayer is questioning your praying and delaying your answers.