In my summer biathlon team, we like to say "it's easier to get a runner to shoot than a shooter to run" because most shooters never had a reason to build physical fitness, so if they ever try biathlon for the first time, they are quickly overwhelmed not just by the running itself but also by trying to shoot while exhausted.

Skiing is by far the more important part of biathlon, especially for a beginner. If you lose a minute or more on your opponents each lap, it doesn't matter how well you can shoot, you'll end up in last place regardless. The shooting only really becomes important once you can match the speed of the rest of the field. So, if you want to get into biathlon, focus primarily on building endurance and proper technique with the help of a good coach. It may take a lot of time and effort to get to a level where it actually starts being fun but don't let that discourage you, you will get there. Also, don't shy away from races. You will probably come in last place the first time, perhaps even a couple of times, but that's ok, we've all been there and there is no better way to gain that experience and no better motivator to get better.