30 minute nap - 4.5 month old

Ladies, I need some words of encouragement!! My beautiful little girl is unable to get through the first sleep cycle in order to nap longer than 30 minutes. She sleeps fine in the car but naps at home are 30 minutes. I do everything the books suggest, dark cool room, follow awake cues, have consistent routines, etc. As many of you know this an exhausting way to spend your day!

My question is - does this issue resolve itself or should I invest in sleep training.

What has been your experiences with sleep training? Is it worth the heartache?