You might've been absorbed by dunia a bit to much than you're supposed to be so much so that you forget about your here after. You need to pause and have a retrospective. Try taking an hour long walk and revaluate yourself. Acknowledge your wrong doings and try rectifying them by istighfar and doing good deeds. Iman strengthens and weakens from time to time. It strengthens by doing good deeds so make sure to do a lot of dikir.
Allah عز وجل said.
قُولُ اللَّهُ عَزَّ وَجَلَّ أَنَا عِنْدَ ظَنِّ عَبْدِي وَأَنَا مَعَهُ حِينَ يَذْكُرُنِي فَإِنْ ذَكَرَنِي فِي نَفْسِهِ ذَكَرْتُهُ فِي نَفْسِي وَإِنْ ذَكَرَنِي فِي مَلإٍ ذَكَرْتُهُ فِي مَلإٍ خَيْرٍ مِنْهُ وَإِنِ اقْتَرَبَ إِلَىَّ شِبْرًا تَقَرَّبْتُ إِلَيْهِ ذِرَاعًا وَإِنِ اقْتَرَبَ إِلَىَّ ذِرَاعًا اقْتَرَبْتُ إِلَيْهِ بَاعًا وَإِنْ أَتَانِي يَمْشِي أَتَيْتُهُ هَرْوَلَةً
Allah the Exalted says i'm at the thought of My servant as he thinks about Me, and I am with him, as he remembers Me. And if he remembers Me in his heart, I also remember him in My Heart, and if he remembers Me in assembly I remember him in the assembly, better than he (does that), and if he draws near Me by the span of a palm I draw near him by the cubit, and if he draws near Me by the cubit I draw near him by the space (covered by) two hands. And if he walks towards Me, I rush towards him.
Hadith of the Prophet Muhammad (saws) in English and Arabic
sunnah.com
Get away from distraction and infatuation with dunia. Allah سبحانه وتعالى said.
وَاصْبِرْ نَفْسَكَ مَعَ الَّذِينَ يَدْعُونَ رَبَّهُم بِالْغَدَاةِ وَالْعَشِيِّ يُرِيدُونَ وَجْهَهُ ۖ وَلَا تَعْدُ عَيْنَاكَ عَنْهُمْ تُرِيدُ زِينَةَ الْحَيَاةِ الدُّنْيَا ۖ وَلَا تُطِعْ مَنْ أَغْفَلْنَا قَلْبَهُ عَن ذِكْرِنَا وَاتَّبَعَ هَوَاهُ وَكَانَ أَمْرُهُ فُرُطًا
And keep yourself patient [by being] with those who call upon their Lord in the morning and the evening, seeking His countenance. And let not your eyes pass beyond them, desiring adornments of the worldly life, and do not obey one whose heart We have made heedless of Our remembrance and who follows his desire and whose affair is ever [in] neglect.
Try reading a bit of quran at a daily bases and watch a bit of reminders for this would inshallah increase your iman. Repent from thonob by doing istighfar, salah and good deeds for allah سبحانه وتعالى said in his quran.
وَأَقِمِ الصَّلَاةَ طَرَفَيِ النَّهَارِ وَزُلَفًا مِنَ اللَّيْلِ ۚ إِنَّ الْحَسَنَاتِ يُذْهِبْنَ السَّيِّئَاتِ ۚ ذَٰلِكَ ذِكْرَىٰ لِلذَّاكِرِينَ
Perform the prayer at the borders of the day, and during the approaches of the night. The good deeds take away the bad deeds. This is a reminder for the mindful.
You can start today by doing salah and reading surat al kahf.