Your resting pulse is actually one of the better things to know before you start your exercise program. It isn't a matter that if yours is 44 you don't need to exercise -- you have to do the exercise to get the health benefits. Keeping an eye on your resting pulse is useful in two senses. First, as you get in to better shape, your resting pulse will generally drop. Not talking about going to 44 from 90 in a couple weeks, but you'll see it edge downward over time. What causes this is that as you do aerobic exercise, your heart starts shoving out more blood with each pulse. So you don't need as many pulses to keep plenty of blood moving.
Second, one of the biggest errors beginners make is to train too hard, too often. (This also means you even if you used to be in excellent shape, but that time was more than a few months back; sadly it also means me as it's a while since I was really doing the sort of exercising schedule I'd prefer*.) As you make this mistake, you'll see your resting pulse rise over time -- and the time scale for the rise is a matter of days. If your resting pulse has climbed by 10%, it's probably a good idea to go easier on your aerobic work today. If it's up 20%, you definitely want to back off the aerobics and do something else good for your health.
Of course there is more to getting started than that ...
One thing, by the way, that I strongly recommend is something it seems few people like to do, but has been one of my most valuable things. Namely, keep a record of what you do and how you feel. Particularly when you're getting started, marking down what your resting pulse is each day is a good idea. Now you don't have to be elaborate, and you don't have to be terribly accurate. 'walk/run for about 30 minutes' is fine. 'felt like dogmeat afterwards' is also fine. You'll probably want to figure out why you felt like dogmeat later -- maybe there's a pattern. One reason I've found it useful is just that business of figuring out what it is that caused me to have a bad workout.
But a more universal reason is, as you keep getting your good workouts in, you'll see changes in what you feel is a difficult workout. Early on, run 1 minute, walk 4, repeat through totalling 30 minutes may well earn the comment "very hard workout". A couple months later, it'll be run 4 minutes, walk 1, repeat to a total of 30 minutes that earns the same comment. This is progress! Congratulate yourself! Seeing that progress is one of the crucial ingredients to staying with an exercise (or any) program.
 Something many folks who do aerobic exercise have heard is some nonsense about how you 'only have so many beats in your heart', so the person who doesn't exercise refuses to do so because he doesn't want to 'waste' his pulses on exercise. Two realities: a) your heart does not have a limit to how many times it can beat and b) even if it did, exercising would be even more important to do. Suppose your resting rate is 72 beats per minute with no exercise; you raise it to 160 for 30 minutes of exercise each day (average), but your resting pulse drops to 60. The exercising person's heart beats 14,280 times fewer each day. That's about 14%. If that limited number of pulses theory were correct, the exerciser has added about a decade to his life expectancy!
* I hate it when my advice applies to me!
While I will generally be mentioning running as the exercise, that's just because it's the one I like. Substitute any aerobic activity you like anywhere you see me say 'run'. And, even if your target is to run, start with walking (which is where I am anyhow).
One important question you probably can't answer by yourself is "Is it medically ok for me to start this sort of exercise program?"
Some informational matters to start with, or questions to answer:
- What is my resting pulse?
- What is my current weight?
- Where could I go run?
- Is there anybody I know that I could run with?
- Are there any running clubs in my area?
- that are friendly to beginners like me?
- that have beginning runner programs?
- that meet at a time and place convenient for me?
- What time of day, or days of the week will I be most likely to exercise at? (The same time as you're normally picking up your kids from school/practice/friends/... is not such a time :-)
- Do I have appropriate equipment?
- Where could I buy some?
- How much do I really need to get?
- What are my most likely excuses for not doing my workouts?
- What can I do to remove those obstacles?
- What are some good answers I can give myself when I try to pull out one of those excuses?
One thing is, everybody, and I do mean everybody, has days when they don't 'feel like' doing their planned workout. It just happens, and that includes for experienced marathoners no less than beginners. So it's good to have in hand some answers that you'll believe about why you're going to get out the door and do your run (or go to the basement, ...). "I'm doing this for my health", "I'm doing this to wear my skinny jeans." are a couple popular answers. But think about what is meaningful for you.
The obstacles are, again, very dependant on the person. I've discovered that if I have to go hunting for my shoes and such, I'm unlikely to get my workout in. More importantly, I'm definitely an evening runner, so I should plan for evening runs. But evening means after work. I've discovered, also, that if I come home and sit down for a bit (maybe catch something on TV, or read something good, or talk to my wife about our days, ...), it's almost certain that I'm not going to get out for my workout. So two of my answers are a) keep my running gear handy and, preferably, near the door and b) go straight straight back out for my workout when I get home; do not sit down. It's also a good idea to have your own answers for 'if it is cold out, I will ...', 'if it is rainy out, I will ...'.