The importance of time can be realized, knowing that Allah swears by it in the Qur’an: “By Al-Asr (the time)” [Qur’an 103:1]
The Prophet (sal’Allahu alayhi wasalam) said: “There are two blessings which many people do not make the most of and thus lose out: good health and free time.” [Sahih Bukhari, 6412]
Imam Ibn Al-Qayyim (may Allah have mercy on him) said: "Wasting time is worse than death; because death separates you from this world but wasting time separates you from Allah."
If a believer truly tries, he can make his entire day an act of ibadah for Allah (SWT). Here are just a few examples of productive & healthy pastimes that I could think of:
1. Exercising (because Allah loves a fit & healthy believer)
2. Caring for and spending quality time with our spouses (an act pleasing to Allah and worthy of great merit & reward insha'Allah)
3. Nature walks & hikes (to admire the beautiful creations of Allah & reflect upon them)
4. Sometimes a good Nature Documentary can boost your emaan to unimaginable heights (I recommend BBC's PLANET EARTH, 5 DVD set)
5. Learning history of the world (the beginnings & ends of the nations of the past)
6. Reading Islamic books (books of tafsir, hadith, seerah etc.)
7. Gardening, arts & crafts, calligraphy
8. Brushing up your skills in target shooting (be it archery, pistol shooting or rifle etc.)
9. Visiting the family & close friends (to maintain the ties of kinship)
10. Finding good, righteous friends with whom you can regularly meet to discuss ideas (not people!)
11. Getting involved in da’wah (via various media that are available)
12. Learning a beneficial new skill (e.g. a specific computer software or application)
13. Listening to lectures via audio/video or attending them in person – taking summarized notes and distributing them to those whom you know
14. Taking part as a volunteer in a charity organization for the sake of Allah... and so on.
Please do share if you too have some great ideas!
I pray that may Allah guide us to the straight path and allow us to make the most of our time.