The first several weeks of breastfeeding my daughter were challenging and painful.
I didn't know how to nurse, and I didn't get much guidance from the hospital's lactation consultants about how to nurse (specifically how to latch and de-latch) properly. As a result, I ended up doing superficial damage to my nipples - mostly bruising and torn tissue - that took time to repair.
In addition, I had an abundant supply in the first several weeks, which meant I leaked constantly and occasionally had plugged ducts on one side. Fortunately, my daughter was a good and patient nurser, and I was able to use a nipple shield on one side until my breast healed.
By the time she was 10 weeks old, nursing was no longer painful, and in fact was quite enjoyable. The plugged ducts continued pretty much throughout nursing, but I was able to clear them quickly most of the time.
I returned to work after 3 months, at which point I started pumping in the day and nursing morning and night.
Pumping presented its own challenges, but on balance, the mix of pumping, nursing, and eventually incorporating formula worked well for me, my daughter, and our family.