A person should proceed level by level in his prayers, and not spend all his energy at the beginning. Rather, he should start slowly, and in the middle, attach himself with great cleaving [to G-d]. Then, he will even be able to say the words of prayer quickly.⁷ p.4b). Even though he cannot pray with mystical attachment at the beginning of the prayers, he should still say the words with great concentration. He should keep applying himself slowly, until G-d helps him to pray with great attachment. Tzava’as HaRivash, p.4a

footnotes: ⁷ The Baal Shem Tov taught: “Sometimes it is possible to pray very quickly, because one’s heart burns fiercely with the love of G-d, and the words come out by themselves” ( Tzava’as HaRivash