Spiritual strength is a bit like physical strength – if you don’t allocate time to it, it is foolish to think it will improve.
So, a key is to figure out how to allocate time consistently to develop spiritually. The classic formula for this is pray in the morning and then in the evening. First in the morning is a time pregnant with possibility, before the concerns of the day have a chance to distract or preoccupy the mind. Just before bed is particularly interesting because it can prime the mind to work on problems while asleep (but the downside is people are often tired at this point, even falling asleep if they attempt to pray). Regardless, figure out a time that might work for your schedule, and then develop it into a habit.
Allocating time is the first step. Then, you have to get results, so the question becomes how to get more rapid results – again, just as with developing physical strength. A person can set aside time for developing physical strength, but not get rapid results, and so with spiritual practice. So, you need to be experimenting, reading, trying things, and noticing what works for you – what gets results.