To miss putting on tefillin is a bittul mitzvas asei, r”l. This carries a chiyuv korban!
If you’ve gotten yourself into a rut and missed, then change from TODAY! If you find it difficult to go to shul then at least put on at home and at least say the minimum with them on eg maybe just shema? Not paskening. Check with your LOR. And just remember: you are not doing Hashem the favor; its the other way round!