(א) אין עומדין להתפלל אלא מתוך כובד ראש. חסידים הראשונים היו שוהים שעה אחת ומתפללים כדי שיכונו את לבם למקום. אפילו המלך שואל בשלומו לא ישיבנו; ואפילו נחש כרוך על עקבו לא יפסיק .
(1) [One] should not stand up to pray unless he is in a serious frame of mind {lit. "heavy of head"}. The original pious ones used to wait one hour and then pray, in order to direct their hearts towards the Omnipresent. [While one is reciting Shemoneh Esrei,] even if the king greets him {lit. "asks about his welfare"}, he should not respond to him, and even if a snake wraps around his heel, he should not interrupt.
Isaac instituted the afternoon prayer service; as it is said, "And Isaac went out to meditate in the field at evening time" (Gen. xxiv. 63) — there is no "meditation" [sihah] that is not prayer; as it is said, "A prayer of the afflicted when he faints, and pours out his complaint [sihah] before the Lord" (Ps, cii. 1).
“Many who live their lives as Jews, even many who pray every day, live on a wrapped and refrigerated version of prayer. We go to synagogue dutifully enough. We rise when we should rise, sit when we should sit. We read and sing along with the cantor and answer ‘Amen’ in all the right places. We may even rattle through the prayers with ease. We sacrifice vitality for shelf-life, and the neshomoh, the Jewish soul, can taste the difference."
A little with kavanah (focus, intention) is better than a lot without.
God doesn't count the number of words you say, She counts the time you spend with Her.
Upon coming in from the “outside” (i.e., from his physical and material concerns), a person should not hasten to pray immediately. Rather, he ought to wait until he discards and dispels his earlier concerns so that they won’t disturb him.”