Long Distance Advice

So my boyfriend and I are 20. We've been together about 6 months and I just have this feeling that he could be 'the one'. I'm leaving for vet school in September and he feels that we should go our separate ways because I'll be gone 4 years and he's still has 4 years of university to finish as well. However, I will be able to visit as my sibling is starting at the same school we are currently attending. I feel like we should give long distance a try and if it doesn't work then ok. Does anyone have any advice on how they talked to their SO about long distance or how they made it work (or why it didn't work)? Thanks so much.