Messenger of Allah ﷺ used to fast till one would say that he would never stop fasting, and he would abandon fasting till one would say that he would never fast. I never saw Messenger of Allah ﷺ fasting for a whole month except the month of Ramadan, and did not see him fasting in any month more than in the month of Sha'ban.  

كَانَ رَسُولُ اللَّهِ ﷺ يَصُومُ حَتَّى نَقُولَ لاَ يُفْطِرُ وَيُفْطِرُ حَتَّى نَقُولَ لاَ يَصُومُ فَمَا رَأَيْتُ رَسُولَ اللَّهِ ﷺ اسْتَكْمَلَ صِيَامَ شَهْرٍ إِلاَّ رَمَضَانَ وَمَا رَأَيْتُهُ أَكْثَرَ صِيَامًا مِنْهُ فِي شَعْبَانَ  

The Prophet ﷺ never fasted in any month more than in the month of Sha'ban.

He used to say, "Do those deeds which you can do easily, as Allah will not get tired (of giving rewards) till you get bored and tired (of performing religious deeds)." The most beloved prayer to the Prophet ﷺ was the one that was done regularly (throughout the life) even if it were little. And whenever the Prophet ﷺ offered a prayer he used to offer it regularly.  

لَمْ يَكُنِ النَّبِيُّ ﷺ يَصُومُ شَهْرًا أَكْثَرَ مِنْ شَعْبَانَ فَإِنَّهُ كَانَ يَصُومُ شَعْبَانَ كُلَّهُ

وَكَانَ يَقُولُ خُذُوا مِنَ الْعَمَلِ مَا تُطِيقُونَ فَإِنَّ اللَّهَ لاَ يَمَلُّ حَتَّى تَمَلُّوا وَأَحَبُّ الصَّلاَةِ إِلَى النَّبِيِّ ﷺ مَا دُووِمَ عَلَيْهِ وَإِنْ قَلَّتْ وَكَانَ إِذَا صَلَّى صَلاَةً دَاوَمَ عَلَيْهَا  

The Prophet ﷺ never fasted a full month except the month of Ramadan, and he used to fast till one could say, "By Allah, he will never stop fasting," and he would abandon fasting till one would say, "By Allah, he will never fast."  

مَا صَامَ النَّبِيُّ ﷺ شَهْرًا كَامِلاً قَطُّ غَيْرَ رَمَضَانَ وَيَصُومُ حَتَّى يَقُولَ الْقَائِلُ لاَ وَاللَّهِ لاَ يُفْطِرُ وَيُفْطِرُ حَتَّى يَقُولَ الْقَائِلُ لاَ وَاللَّهِ لاَ يَصُومُ