1. (कभी कभी) / (कभी कभार​) आप के पास जो कुछ भी है उसके लिए (कृतज्ञ) / (शुक्रगुज़ार​) होना बहतर है । (kabhii kabhii) / (kabhii kabhaar) aap ke paas jo kuchh bhii hai uske liye (kritagya) / (shukrguzaar) honaa behtar hai Sometimes it is better to be grateful for whatever you have. (You can drop भी "bhii" from the Hindi sentence and it will then mean "what" in place of "whatever". I've added "bhii" as it sounds more natural to me that way) 2. जितना अधिक हम स्वयं को पाठन सामग्री से परिचित रखेंगे उतना ही अधिक हम सीखेंगे । jitnaa adhik ham svayam ko paathan saamagrii se parichit rakhenge utnaa hii adhik ham siikhenge The more we keep ourselves acquainted with study material, the more we will learn. 3. यह एक उल्लेखनीय घटना बन चुकी है कि वृद्ध, युवा लड़कों और लड़कियों को रूपवान पुरुशों और सुंदर महिलाओं में परिवर्तित होते देख पा रहे हैं । yeh ek ullekhniiya ghatnaa ban chukii hai ki vriddha, yuvaa ladkon aur ladkiyon ko ruupvaan purushon aur sundar mahilaaon men parivartit hote dekh paa rahe hai It has become a phenomenon that the elderly are able to see young boys and girls transform into handsome men and beautiful women. I take it that sentence 3 is hinting at increased life expectancy?

Yes. That's what I meant.

I am not clear about the "material" in your second sentence. What kind of "material" is meant here? Do you mean "study material"?

Sometimes it is better to be thankful for what you have जो भी तुम्हारे पास है उसके लिए कृतज्ञ होना कई बार अच्छा होता है ।