There are jobs that you should let professionals do, and jobs that anybody average Joe can do if you put forth any effort.
Like Cali said, if it's setting up landscaping from scratch, I'd ask for help because who knows what you need for irrigation and a professional look to things. If it's just you changing out some plants, weeding, throwing down mulch, and mowing the lawn ... that's different.
I would have got somebody to do my roof, because there's a big difference between somebody doing it right and me doing it. I've helped put roofs on houses before on mission trips down to various places, but when a massive storm comes through, I'd want to be a dry knowing that somebody who actually knows what they're doing did the work. For the record, I just paid to have my roof replaced ... thankfully insurance helped with 95% of it.
In the end, that's up to you if you want to spend extra money so you can sleep in on the weekends. Personal choice. Not really our business. But you asked, so we give our opinions.