Sincerity and Significance of Intentions and all Actions,Reward will be,even not able to do physically for valid reason.

وعَنْ أبي عَبْدِ اللَّهِ جابِرِ بْنِ عَبْدِ اللَّهِ الأَنْصَارِيِّ رضِيَ الله عنْهُمَا قَالَ :آُنَّا مَع النَّبِيِّ صَلّى اللهُ عَلَيْهِ وسَلَّم في
وَفِي « إِنَّ بِالْمَدِينَةِ لَرِجَالاً مَا سِرْتُمْ مَسِيراً ، وَلاَ قَطَعْتُمْ وَادِياً إِلاَّ آانُوا مَعكُم حَبَسَهُمُ الْمَرَضُ » : غَزَاة فَقَالَ
رَواهُ مُسْلِمٌ . « إِلاَّ شَرآُوآُمْ في الأَجْرِ » : روايَةِ
ورواهُ البُخَارِيُّ عَنْ أَنَسٍ رَضِيَ اللَّهُ عَنْهُ قَالَ :رَجَعْنَا مِنْ غَزْوَةِ تَبُوكَ مَعَ النَّبِيِّ صَلّى اللهُ عَلَيْهِ وسَلَّم فَقَالَ:
.« إِنَّ أَقْوَامَاً خلْفَنَا بالمدِينةِ مَا سَلَكْنَا شِعْباً وَلاَ وَادِياً إِلاَّ وَهُمْ مَعَنَا ، حَبَسَهُمْ الْعُذْرُ »
4. Jabir bin Abdullah Al-Ansari (May Allah be pleasedwith them) reported: We accompanied the Prophet (PBUH) in an expedition when he said,
"There are some men in Al-Madinah who are with you wherever you march and whichever valley you cross. They have not joined you in person because of their illness.'' 
In another version he said:
"They share the reward with you.'' [Muslim].

It is narrated by Bukhari from Anas bin Malik (May Allah be pleased with him): We were coming back from the
battle of Tabuk with the Prophet (PBUH) when he remarked,

 "There are people whom we left behind in Al-Madinah
who accompanied us in spirit in every pass and valley we crossed. They remained behind for a valid excuse.''

Commentary: What we learn from this Hadith is that if the intention and spirit of Jihad(striving in the path of Allah)/any other  good action are present in the heart of a
Muslim but physically he is unable to take part in it for valid reasons, he will get the reward of good action without even
his actual participation in it........Wallah Allah is ready to give Fault is on our Part........ it comes that if someone make intention for Tahajjud Prayer and not able to wake up Allah will give him Reward...........Be Ready to take it ans make the book of deed Bright. (Do Dua for me)