The Hebrew word for diligence is zerizut. Zerizut translates to alertness, enthusiasm, agility, nimbleness, alacrity, expedition, smartness, briskness.
Find a comfortable seat in a quiet place. First, take a few deep breaths. Deep breathing brings oxygen to your brain and helps clear the mind. Close your eyes. Continue breathing until you feel relaxed.
The focus of this meditation will be upon climbing towards Hashem in our tasks/goals. Using a phrase from Psalms 139 for meditation, choose whether you will say the Hebrew or the English. Repeat it until you are comfortable with it and can say it from memory:
אִם־אֶסַּק שָׁמַיִם שָׁם אָתָּה
(Im esaq Shamayim sham Atah)
Meditate on this phrase above (either Hebrew or English) for at least 10 minutes without interruption. As you are meditating on this phrase, try and bring your mind to goals or tasks you have difficulty accomplishing, or setbacks that are before you.
Imagine that a ladder is before you. Slowly begin to climb this ladder, rung by rung. Continue meditating on the phrase above, realizing that as you are climbing, you are drawing nearer to your goal. Keep your sights on the rung just above you - no higher. Realize your climb is towards Hashem and to achieve what is in His will. Continue to climb these rungs, one at a time: slowly, diligently, deliberately.
Try and truly imagine the climb, the gentle and persistent movement - hands on the rungs, feet on the rungs.
Keep your sights above, looking for the next rung, and don't stop climbing.
As you slowly and gently end your meditation by opening your eyes, try to maintain a sense of quietness for a time after - allow the experience to flow through you and feel its effect. Try and take with you what you have gleaned from this meditation. By being more at ease, viewing the "rungs" of life in your mind, you can come away from this kind of introspection ready to be diligent in your daily walk and confident in the end goal: to reach Hashem, one rung at a time, through purposeful living.